Cognitive Aging

Learning Outcomes

By the end of this chapter, readers will be able to:

1. Understand the underlying assumptions and key tenets of healthy cognitive aging across the life span.

2. Describe methodological issues that should be considered in review of research regarding healthy cognitive aging.

3. Discuss current literature regarding healthy cognitive aging across the life span including basic and higher order cognitive processes.

4. Describe current theories of healthy cognitive aging.

5. Identify strategies to assist individuals with the promotion of positive aging including cognitive health.

clinical Vignette

Bill Thompson is a 75-year-old retired man who has been happily married for 50 years. Bill is in good physical health and has not experienced noteworthy changes in his cognitive abilities. He stays active by swimming 4 days a week, volunteers at a youth center, and regularly socializes with friends and family. Throughout Bill's life, he has been engaged in physically and mentally stimulating activities, such as playing chess, walking his dog in the park every day, and coaching the Local youth swim club.

Overall, Bill is as mentally sharp as he was when he was younger, and compared with middle-aged adults, his performance on a wide range of neuropsychological assessments is similar. To some, Bill may not fit the stereotypical image of what happens when you age (that is, forgetful, withdrawn, dependent on others, physically frail). Bill, however, exemplifies healthy cognitive aging.

1. What is healthy cognitive aging? What characteristics of healthy aging does Bill demonstrate?

2. What factors impact cognitive health? Which of these factors are seen in Bill's circumstances?

3. How do older adults develop and maintain healthy cognitive processes across the life span?

W

that happens to our cognitive abilities. as we age?

Do we gain new knowledge and information? Do we experience decreases in how fast we mentally process information? Do we perform similarly to younger adults on certain. tasks? Surprisingly, the answer to each of these questions is "yes!" You may, be wondering how this can be. The answer reflects several essential tenets of cognitive aging that we will discuss in further detail. Historically, it was thought and widely believed that individuals inevitably experience cognitive decline as they age.

Furthermore, it was thought these cognitive changes were experienced universally across individuals and across cognitive abilities (for example, memory, language, decision-making). However, research has found a more complex (and interesting) pattern of results. Healthy cognitive aging does not occur in a vacuum, nor does it start at a specific age. For example, an individual does not wake up on his or her 50th birthday and experience notable cognitive (or physical) changes: Cognitive aging is a process that unfolds over decades.

In fact, some cognitive processes begin to change as early as age 25. This chapter reviews healthy, normal, age-related effects on cognition, including basic and higher order cognitive processes, and theories of cognitive aging. Implications of these age-related effects are discussed in terms of how to optimize cognitive functioning across the life span and specific strategies that may be used to enhance rehabilitative outcomes.

Bases of Cognitive Aging

Key Tenets of Cognitive Aging Across the Life Span

When describing differences between older and younger adults, cognitive aging studies typically use language that disproportionately reflects negative aspects of the aging process, such as "deficits," "losses," "decrements," and "impairments." It is important to note these findings are based on lab-based experiments that reflect differences in reaction time (in the range of milliseconds) or decreases in accuracy (by 1 to 2 stimuli) between younger and older adults. These results and the language used to describe findings can be misleading in understanding how cognitive aging unfolds in real-world and clinical settings and can perpetuate negative stereotypes of older adults. It is therefore important to consider the implications of using potentially negative or emotionally charged language that may have unintended consequences for older and younger adults, laypersons, clinicians and professionals, and policy makers. To illustrate, Levy, Slade, Kunkel, and Kasl (2002) reported that 85 percent of adults over age 50 years have experienced ageism and that an individual's attitudes toward aging have been found to predict mortality. Additionally, it has been found that older adults are more likely to internalize these negative stercotypes of aging. Older adults exposed to negative stereotypes showed declines in performance on memory, math, and handwriting tests as well as increased level of self-induced dependence, which may lead to learned helplessness. Additionally, assumptions of these negative stereotypes can lead to less optimal or appropriate treatment. We have made a conscious decision in this chapter to avoid stereotypical or negatively charged language and to use words that more accurately describe cognitive aging, such as"changes" and"differences" and, when appropriate for describing the nature of these differences,"gains,""declines," and"stability."

When studying cognition across the life span, it is important to use conceptual frameworks that aid in the understanding and interpretation of results. For the purpose of this chapter, the following tenets are used collectively to understand and interpret cognitive changes and to delineate how best to optimize cognitive aging throughout the life span. Clinicians and rehabilitation professionals should take these tenets into account collectively when assessing and implementing any plan of care because cognitive aging is influenced by a wide array of factors.

Tenet 1: Cognitive aging is best understood using a developmental life span approach that considers cognitive development a lifelong process that begins with conception and end with death. The developmental life span approach takes into consideration normative age-graded influences, normative sociohistorical influences, and nonnormative life events. Normative age-graded influences are biological or environmental life influences or experiences that are the same for all individuals at a given developmental timeframe.

An example of a biological or maturational process would be puberty or the social norm of adolescents driving at age 16. Normative sociohistorical influences are biological or environmental life influences or experiences that are generation or cohort specific. An example would be differences across generations in nutrition, education, or technology because these have changed dramatically over the past 100 years. Another example would be exposure to cohort-specific experiences such as the Great Depression or 9/11. Nonnormative life events are biological or environmental life influences or experiences that are unusual or atypical for an individual. An example would be the loss of a parent at a young age, becoming a widow at age 20, or having a serious medical condition as a child. This tenet is important because it underscores the importance of lifelong development and the concept of plasticity. Plasticity is the ability of the brain to learn, adapt, and modify across the life span. The concept of neuroplasticity is discussed further in Chapter 25. The implication of this tenet is that what happens early in life, in terms of factors such as nutrition, illness, or education, has an impact on development later in life, and as a developmental process, cognition is mal-leable or pliable rather than unchangeable.

Tenet 2: Cognitive aging occurs within a framework of gains, declines, and stability. This tenet highlights findings that have shown cognition in later life is multidimensional and multidirectional rather than a universal and linear decline across all cognitive processes. The implication of this tenet is that some cognitive processes improve with age, some change compared with younger adults, and other processes remain stable throughout the life span.

Tenet 3: Cognitive aging is influenced by and incorporates a wide range of inter-and intraindividual differences, including but not limited to lifestyle factors such as diet, exercise, health habits, and education. Interindividual differences reflect variation among groups, whereas intraindividual differences reflect variation within an individual. These influences are important for distinguishing between-group differences and within-group differences across the life span.

Methodological Considerations One of the challenges when studying cognitive aging is the selection of the appropriate research design and the resulting implications of study findings. For example, cross-sectional research designs—those that study several groups at a particular point in time—tend to exaggerate group differences between younger and older adults, implying a rather steep decrease in cognitive processes. Other, more sophisticated research designs (for example, sequential research designs that study participants over time) show less extreme differences between younger and older adults, indicating more stability across the life span in many cognitive processes. A more detailed discussion of research design and the implications for understanding cognitive aging can be found in the online ancillaries.

Foundations of Cognition Aging: Basic and Higher Order Cognitive Processes

Using a developmental life span approach, this section discusses how cognitive processes are affected over an individual's life. Cognitive processes are categorized as basic and higher order. Basic cognitive processes serve as the foundation or building blocks for higher-order cognitive processes and include sensory and perceptual processes, attention, short-term memory, working memory, and long-term memory systems.

Higher order processes typically require additional cognitive resources and are conceptualized as more complex processes. Examples include reasoning, decision-making, problem-solving, judgment, abstract thought and logic, and language production and comprehension processes. Higher order cognitive processes also include everyday problem-solving, everyday cognition, wisdom, and expertise.

Two additional concepts that are discussed are implicit and explicit processing and overall intellectual abilities.

Basic Cognitive Processes

Sensory Processes

Sensation is a biological process that is responsible for transmitting incoming stimuli (or information) from the environment to the appropriate neural structures in the brain. Increased age is associated with decreasing auditory and visually based processing, Auditory decline is evidenced by difficulties hearing low-and high-level thresholds, aging of the cochlea, and decreased processing of auditory information, Visual decline is evidenced by decreases in the amount of light entering and hitting the retina, increased susceptibility to glare, decreased peripheral processing, and presbyopia (that is, farsightedness due to the aging process). Age-related declines in auditory and visual processing begin in middle age and continue throughout old age. Research has found that auditory and visual processing declines are associated with a decrease in fluid abilities, one of the main components of intellectual ability. These findings imply that certain cognitive abilities and biological aspects may age together. Another key issue is the impact sensory processes may have on cognitive abilities.

If visually or auditory based information is processed through a less optimal system, subsequent cognitive processing of information may result in errors or take additional time. For example, an older adult experiencing moderate hearing loss may need to listen to a voicemail message multiple times to fully process and understand the message. The extra time needed is due to degraded information received from the auditory system and not to lack of language comprehension or memory. It is important to understand how sensory processing is inextricably linked to basic and higher order Cognitive processing and, more important, the real-world and clinical implications of this. Sensory processes are described in greater detail in Chapter 9. Perception

Perceptual processing describes the process of assigning meaning to incoming serisory stimuli. For example, when shown a picture of a dog, recognizing and correctly naming the object"dog" is the process of perception. Perception is considered an automatic and extremely fast cognitive process that occurs without awareness or intention most times. Overall, older adults have been found to successfully use situational context and their vast experience to maintain the perceptual abilities necessary for everyday functioning.

Attention As conceptualized by Kahnaman (1973), attention is a resource-limited cognitive process that is necessary for supporting proper functioning of all other cognitive abilities, especially higher order cognitive processes. The ability to successfully make decisions, problem-solve, or think through an issue requires attentional resources. For example, reading this book chapter becomes increasingly more difficult when your attentional resources are taxed because of other interfering stimuli (for example, loud music, people talking).

In a clinical setting, four types of attention are described; these include the following, in order from simplest to most complex: sustained (or focused) attention, selective attention, alternating attention, and divided attention. Throughout the day, individuals continuously shift between these different types of attentional processes depending on the needs of a given task. Cognitive aging researchers use a variety of neuropsychological measures to examine how these types of attention are affected throughout the life span.

Sustained (or focused) attention is the ability to direct attentional resources to a single task or activity, such as reading a book. When comparing younger and older adults' performance on measures of sustained attention, no statistically significant differences are found. Selective attention is the ability to direct attentional resources to a task or activity while simultaneously directing attentional resources to ignore distracting information. As an example, watching a favorite television program while trying to ignore friends talking in the other room would involve directing attentional resources to watching the television show while also directing attentional resources to not paying attention to the chatter from the other room. In other words, attentional resources are needed to ignore distracting information, stimuli, or tasks.

Overall, mixed results have been found when comparing the performance between younger and older adults on measures of selective attention, ranging from no age-related findings to reduced inhibitory control during selective attention tasks. On standard neuropsychological assessments, age-related differences have been found (Barr & Giambra, Haring et al., Plude & Doussard-Roosevelt, Uttl & Pikenton-Taylor, 2001), but these results are not consistent across all studies. For example, in a meta-analysis reviewing multiple studies, Verbaghen and Cerella (2002) found no age-related differences in selective attention. Additionally, these age-related differences in selective attention are reduced in tasks where the individual has had prior experience or practice, Alternating attention is the ability to direct or switch attentional resources between two or more tasks or activities. It is conceptually distinct from divided attention because tasks are performed one at a time with attentional resources flexibly switching back and forth between tasks.

For example, switching between numbers and letters of the alphabet (that is, 1, A, 2, B, 3, C, 4, D, 5, E, etcetera) is an example of a task that requires alternating attention. Research has found significant age-related differences between younger and older adults in alternating attention tasks, with older adults having more difficulty alternating among tasks, Divided attention is the ability to allocate attentional resources to two or more tasks or activities at the same time. Driving while listening to music and carrying on a conversation is an example of using divided attention.

Similar to the other types of attentional resources, divided attention is limited, and, once exhausted, accuracy declines and reaction time increases. Researchers typically use a dual-task paradigm to investigate divided attention in which participants are instructed to complete two tasks at the same time. Participants' dual-task performance is compared with their performance when completing either task separately.

Overall, research has found age-related differences in divided attention, with younger adults performing significantly better than older adults. These findings are especially evident when completing complex tasks like preparing income tax returns, Rogers, Tombaugh, Similar to the findings for selective attention, these age-related differences in alternating and divided attention can be minimized when simpler tasks are tised or participants are given time to practice. For example, researchers found improved walking speed under divided attention conditions. ditions after 12 weeks of practice in older adults with difficulties maintaining balance;

Clinically, these findings are relevant, especially when attention is needed to support other cognitive processes. For example, carrying on a casual conversation with a patient who is learning how to use a walker may negatively affect the therapeutic process because attentional resources are being used for walking, talking, and the new learning required to use the assistive device. Removing distractions and allowing the patient to focus attention on a single task may improve performance. Once the structured task is being performed at a desired level, the clinician may then introduce distractions to challenge the older adult to facilitate greater translation into a real-world environment, such as a busy home or shopping center.

• Several key factors also can affect performance, including motivation and fatigue. This is of particular relevance for allied health professionals (for example, occupational therapists, speech-language pathologists, physical therapists) who are developing and implementing treatment goals for patients. To increase engagement and treatment adherence, it is important to in- chide patients in the process of developing realistic and meaningful goals that they are invested in practicing and achieving.

Interprofessional Practice

Promoting Optimal Function in Oider Adults

With Normal Age-Related Cognitive Changes

Physical therapists, occupational therapists, and speech- language pathologists have a unique opportunity to facilitate optimal cognitive functioning in older adults. In a monograph discussing cognitive enrichment of older adults,

Hertzog and colleagues outline several considerations that should be made regarding individuals behaviors and environmental contexts. One area in which rehabilitation professionals must be sensitive is attitudes and beliefs toward aging because one's perception about aging can e aging process. For example, if an older adult believes aging is predominantly a negative process, this can affect her performance on cognitive tasks. It developmental framework, highlighting the gains, losses, and stability.

and stability.

Attentional Resources

Attentional resources can be affected significantly. by motivation and interest, Imagine being at a theater watching a movie you are not particularly interested in. During the movie, you are distracted by various things (the gentleman loudly eating his popcorn behind you; the teenager talking on her phone). The distractions make you even less. interested in watching the movie, and you end up falling asleep. Now imagine going to see a movie that you are extremely interested in. Even with the same environmental distractors present, you direct all of your attentional resources to the movie while ignoring the irrelevant sensory input.

After the lights come on you think, "I can't believe the movie is already over." This latter scenario illustrates how motivation and fatigue can influence how attentional resources are used and how performance (in this case, watching the movie versus falling asleep in the theater) can be affected. During a therapy session, you should always ask yourself which movie is your patient viewing? Is your patient actively involved in his plan of care, including goal development and goal setting?

If not, your patient is less likely to actively engage in the therapeutic process, become easily distracted and less motivated to practice.

Memory

The term "memory" can be used to describe various types of memory, including sensory memory, short-term memory, working memory, and several long-term memory systems, including declarative and procedural long-term memory.

Extensive research has been conducted on the effects of age and one's memory that reflect gains, declines, and stability. The following sections discuss each of the aforementioned memory systems in more detail.

Sensory Memory

Sensory memory is described as a preattentive memory system that stores incoming sensory information for a very short duration (less than 250 milliseconds) before transferring the information to short-term memory or dropping the information from the system. It is referred to as"preattentive" because we are not consciously aware of the information. By the time you are aware of any given stimuli (for example, a loud noise, scing the word "cat") the information has already been transferred to short-term memory. Overall, research has found minimal to no age-related differences in sensory memory.

Short-Term Memory

Short-term memory stores information. Seven ( ^{#} two) stimuli can be stored for approximately 15 to 20 seconds without rehearsal."Without rehearsal" is an important distinction because a true measure of short-term memory does not enable participants to use any strategies, such as repetition, for remembering information. To assess short-term memory, participants are typically given a simple memory task where they hear a list of stimuli (for example, words or numbers) and must recall as many stimuli as possible immediately or after a short amount of time has elapsed. For example, an individual is verbally presented a list of words at a rate of one word per second (for example, dog, squirrel, fish, rabbit, elephant, ant, giraffe) and asked to immediately recall as many words as possible. Mixed evidence has been found in terms of age-related difference in short-term memory, with some studies finding minimal to nonsignificant age-related differences, whereas others identified significant age-related differences in short-term memory.

Working Memory

Working memory is conceptually distinct from short-term memory because it stores, maintains, and actively manipulates information. For example, when you perform the following math problem in your head, 2 + 3 minus 1 times 4 , you are using working memory. Another example is using the preceding list of animals and mentally rearranging them in size from smallest to largest. Working memory serves an important role in facilitating higher order cognitive processes such as language production and comprehension. decision-making, problem-solving, and learning. Originally conceptualized by Baddeley and Hitch (1974), working memory consists of three interrelated components: the central executive, the phonological (or verbal) loop, and the visual-spatial sketchpad. More recently a fourth component, the episodic buffer, was added. The central executive processes and manipulates information from the two lower systems, the phonological loop and the visual-spatial sketchpad temporarily store and maintain verbal and visual information; respectively.

The episodic buffer has not received extensive investigation but is hypothesized to provide bidirectional linkage from each of the two sub-systems within working memory to the corresponding long-term memory representations. Working memory enables individuals to save new information into long-term memory while concurrently being able to store, maintain, and process information from both visual and verbal outputs. For example, when you give someone directions how to drive from one location to another (for example, school to the mall), you are using working memory.

Promoting Best Practice

Working Memory

A large body of research has investigated the overall construct of working memory and has found significant age-related differences, with younger adults performing better than older adults. Findings from a meta-analysis indicated that as the task complexity or cognitive load increases, age effects increase s well, with working memory span tasks (for example, counting backward by seven) resulting in the largest age-related effects. The specific underlying mechanisms for these changes are not well understood; for example, it is not known whether the central executive, the storage systems (that is, phonological loop and visuospatial sketchpad), or both are responsible for these age-related differences.

From a clinical perspective, therapists must consider how working memory may facilitate or hinder progress. For ex- ample, much of our communication with patients, such as a family or plan of care meeting, relies on spoken communication. As the volume and complexity of information increases, it may be more difficult for patients to maintain, organize, and process all of the relevant information. To minimize this difficulty, therapists can break up sessions to reduce the volume of information or use written reminders. Patients and family members can implement these strategies as well. For example, using daily reminders may be helpful (ie., shopping list, daily tasks, medication adherence checklist), and eliminating background noise and distractions can assist in spoken communication.

Long-Term Memory

Rather than a single system, long-term memory actually comprises several types of memory systems that differ on the basis of the type of information contained and how each system is affected during the aging process. Deciarative Memory Declarative memory is a verbal-based memory system and is further divided into semantic and episodic long-term memory systems. Examples of information stored in episodic long-term memory are personal, autobiographical memories such as your first kiss or your 16th birthday party.

Episodic memory also contains information from more recent learning events. To illustrate, consider the following example. Imagine you participate in a two-part experiment.

For Part 1 of the experiment, you are given a list of 30 words to remember. Part 2 of the experiment occurs 1 week later when you are shown a list of words: 30 from the original list of words (from Part 1) and 30 new words. Your task is to indicate which words are from the original list and which are new words. To successfully complete this task, you will need to remember the specific learning event from the prior week (that is, did I learn this word last week or is it a new word?).

Episodic memory relies on effortful and conscious processing of a particular memory (or learning episode).

Semantic memory stores general world knowledge that is not linked to a specific learning episode. Examples include factual information (for example, who was the first president of the United States?), vocabulary (eg, what does the word "justice" mean?), linguistic rules (eg-, which sentence is correct: He ran down the street or He runned down the street?), and social graces and customs (for example, waving good-bye, saying hello. It is hypothesized that memories are initially stored in episodic memory and then, with additional use, are transferred and stored in semantic long-term memory once the specific learning event is lost. For example, you probably do not remember when you learned the state capital of Ohio was Columbus. However, children who recently learned this information would be able to recall this information, in addition to remembering the specific learning event (for example, in Mrs. Strohscher's class last month during social studies). Eventually, these students will not retain the specific learning event and only retain the information (for example, Columbus is the capital of Ohio) in semantic memory.

Aging appears to affect episodic and semantic long-term memory differently. Age-related differences are consistently found for episodic memory, with younger adults performing significantly better than older adults. These differences are especially evident with memory tasks that require effortful cognitive processing, such as recall or fill-in-the-blank tasks compared with tasks such as recognition, which provides context or cues:

The pattern of age-related differences for semantic memory is quite different compared with that of episodic memory, with older and younger adults performing similarly or, depending on the type of task, older adults performing significantly better than younger adults. For example, on tests of vocabulary ability, older adults readily outperform younger adults. This gain within semantic memory has been attributed to the accumulation of knowledge and experience over the life span. Overall, these data suggest a range of age-related trends in declarative memory that vary from declines (that is, episodic memory) to maintenance and gains (that is, semantic memory) across the life span.

Procedural or Nondeclarative Memory

Procedural or nondeclarative memory is a nonverbal-based memory system that stores information for motor-based skills and behaviors (that is, muscle memory, habits, emotional associations, priming, and classical conditioning. Retrieval of nondeclarative memories can occur with little effort or even conscious awareness. Examples of procedural memory include playing a musical instrument, riding a bike, or performing a habitual task, such as brushing your teeth.

Research indicates that nondeclarative memory is fairly well preserved, with minimal to no age-related declines being noted. Age-related differences are more likely to be found when the complexity of the priming or motor task increases. A clear trend from these findings is the role of task complexity and the subsequent need to use additional cognitive resources. Compared with older adults, younger adults seem to more effectively use cognitive resources when completing difficult tasks compare, For example, driving in an unfamiliar environment under less than ideal circumstances (for example, night, poor weather, high traffic) could be more difficult for an older adult due to task complexity and greater than usual cognitive resources.

Prospective Memory

Prospective memory enables individuals to remember future-oriented or scheduled tasks without the use of external memory aids (eg., written note or list). Examples of prospective memory include remembering to take medications twice a day, wearing a brace to bed, stopping at the grocery store, picking up your dry cleaning, or buying a birthday card for a friend. Many researchers have hypothesized that prospective memory should be significantly affected by normal aging processes due to the cognitive effort required; however, research has found mixed findings depending on the type of prospective memory task, strategic or automatic: Strategic prospective memory requires effortful and conscious monitoring of the environment to remember, whereas automatic or spontaneous prospective memory is usually triggered by an external environmental cue. Studies that have used prospective memory tasks requiring complex or high levels of strategic processing result in dramatic age-related differences. On the other hand, prospective memory tasks that use automatic or spontaneous retrieval processes and require less cognitive resources result in minimal to no significant age-related differences. For example, if an individual needs to stop at the store on the way home from work, it is more likely that individual will remember to do so if the store is actually on the route home because this provides a cue enhancing recall. Evidence suggests tasks relying on spontaneous retrieval are preserved in older adults; therefore, providing cues to rely on these automatic processes could aid older adults with prospective memory tasks.

The clinical implications of prospective memory processes are far ranging and imperative. Adherence with any health behavior relies heavily on remembering to complete a future-scheduled activity. Prospective memory can be supported by facilitating automatic processing.

For example, if a patient needs to wear a brace to bed, automatic processing can be facilitated by visual cues, such as laying the brace on the patient's pillow to decrease the need for strategic processing. Higher Order Cognitive Processes

Executive Functioning

Executive functioning is a global term referring to higher order cognitive processes, such as reasoning, decision-making, problem-solving, judgment, abstract thought, and logic. Overall; research findings have found significant differences between younger and older adults across a wide range of executive functioning tasks. For example, significant differences between younger and older adults have been found on reasoning and judgment tasks, with older adults utilizing less efficient strategies than younger adults. Older adults have been found to be slower in estimation and judgment tasks while being less likely to revise judgment strategies as new information becomes available (Chasseigne et al., Mutter & Pliske, 1996).

In general, age-related differences seem to be greater and more pronounced as task complexity increases and/or as additional cognitive resources are needed to successfully complete the task. For example, when using a dual-task methodology (in which participants complete two cognitive tasks at the same, older adults perform Jess well than younger adults (Neider et al., 2011)). This difference is most likely due to the increased cognitive effort needed to complete two tasks at the same time compared with the cognitive resources required to complete either task alone.

Research also has found that various aspects of executive function may change differentially with age. Goh and Col Cagues (2012) examined different aspects of executive function in a sample of 148 healthy older adults from the Baltimore Longitudinal Study over approximately 14 years with testing every 1 to 2 years. Results found an interesting pattern of age-related differences and stability across a variety of executive functioning related-processes. Specifically, age-related longitudinal declines were found for four types of executive function related processes (that is, inhibition, mamipulation, semantic and phonological retrieval, and task switching), whereas five executive functioning-related processes (that is, abstraction, capacity, chunking, discrimina- tion, and short-term memory) were maintained or showed improvements with age.

Although significant differences have been found on lab-based tasks of executive functioning, little is known about how these findings translate to the real world for older adults. The following sections on everyday problem-solving and everyday cognition explore this important yet under-studied area.

Problem-Solving and Everyday Problem-Solving

An interesting line of research within the executive functioning literature is the research examining problem-solving and everyday problem-solving. Studies of problem-solving typically use nonfamiliar, lab-based tasks that lack external validity, whereas studies of everyday problem-solving use tasks that resemble real-world activities that have high external validity. Significant and consistent age-related differences have been found between younger and older adults for problem-solving. Specifically, research has found older adults tend to use less efficient strategies, persist longer in using erroneous solutions, and produce more errors than younger adults when using problem-solving processes during lab-based tasks. However, these findings are based on lab-based tasks that do not necessarily reflect problem-soiving needed for real-world situations (for example, managing finances, driving, medication adherence). Subsequently, researchers hypothesized that older adults may not perform as well on lab-based tasks because these tasks lack meaning and relevance to older adults and thus potentially reduce older adults' motivation.

For this reason, researchers have advocated using tasks that resemble real-world situations to assess problem-solving. One of the advantages of this approach is the high degree of external validity, as evidenced by the use of real-world situations and tasks, rather than lab-based tasks that older adults may not be familiar with or motivated to participate.

Research findings to date, however, have been mixed when examining everyday problem-solving tasks. Willis (1996) suggests that everyday problem-solving comprises cognitive and noncognitive factors (for example, health status, fatigue levels) and sociohistorical factors (for example, occupation, education level) that, taken together, facilitate older adults' motivation, engagement, and performance. A reason for varied findings may be that current studies have yet to conceptualize everyday problem-solving within this framework as some continue to use hypothetical problem scenarios instead of actual real-world scenarios. Additionally, complexity of a problem-solving task (for example, a single well-defined answer versus ambiguous problem with multiple possible solutions) may lead to differing outcomes. Thus, additional research is needed to tease out alternative operational definitions of everyday problem-solving to best understand the trajectory across the life span.

Everyday Cognition

Everyday cognition is an important yet relatively new research area that examines how the role of cognition is used in everyday or usual activities. Although statistically significant findings have been found on a range of executive functioning lab-based tasks, everyday cognition explores how individuals use cognitive processes in real-world contexts. For example, the differences found between younger and older adults on a variety of lab-based tasks are operationalized and quantified in milliseconds. Additionally, tasks used in cognitive aging research are designed to overload and tax participant's cognitive resources, resulting in decreased accuracy and increased reaction time. Although theoretically informative and interesting, these results do not provide information regarding how older adults use cognitive resources on a daily basis.

In most cases, older adults successfully engage with and complete everyday activities and tasks because their required cognitive resources are not overly taxed or exhausted (Park & Gutchess, 2000; Salthouse and Maurer, 1996; see figure 7 to 1). Additionally, research has found that older adults compensate for age-related differences in memory and attention when completing decision-making tasks by relying on their accrued knowledge and experience with decisions.

Older adults ability to successfully use everyday cognition can be illustrated with research findings pertaining to work performance. Generally, significant age-related differences have not been found between younger and older adults in job performance, Park (2000) attributes this to older adults' ability to effectively use their prior experience and knowledge and specific strategies such as teamwork. This ability not only reflects a gain for elders but also provides support for everyday cognition as an important area that warrants further research. Sterns and Dawson (2012) outline the importance of resilience in overcoming changes in basic cognitive and physical processes to allow for continued success in the workplace, Additional strategies that facilitate effective job performance include job sharing, effective workstation design, and training or retraining. Further information about older adults' work performance can be found in Chapter 20. These findings also highlight the concept of cognitive reserve, which is discussed later in the chapter (see "Optimizing Cognitive Aging and Health"), that has been identified as a key moderating variable in cognitive aging.

Conversely as with other domains of cognition, certain everyday tasks may be more difficult for older adults especially as task complexity increases. For example, novel activities that heavily use executive functioning processes may be more challenging for older adults. A common example can be seen with driving.

Although much of driving is automatic or implicit, other parts, such as merging onto a busy freeway or finding a restaurant in a new city at night, require considerable cognitive resources and faster reactions. Specifically, changes in older adults' executive functioning and speed of processing may come into play in these types of real-world situations. Additional examples of real-world situations that may be more challenging for older adults include maintaining a complicated medication regime or remembering complex instructions from one's physician, key factors to consider when determining whether older adults' everyday cognition and resulting performance may be affected include (1) cognitive processes required, (2) novelty of the task, (3) complexity of the task, and (4) amount of prior experience or practice afforded.

The higher order cognitive process of language comprises production and comprehension processes, Production processes enable individuals to generate and verbalize language, while comprehension processes enable individuals to perceive and understand spoken language, Production and comprehension processes work in tandem to provide effortless and automatic processing and understanding of language. Similar to other cognitive processes, research has found a pattern of age-related gains, declines, and stability within language production and speech comprehension. With respect to comprehension processes, the underlying semantic long-term memory system required to assist in the understanding of words and phrases used in everyday language remains intact, whereas age-related differences can be found for certain aspects of production. Examples include increased word-finding difficulty and increased tip-of-the-tongue experiences (in which the individual can almost, but not quite, recall the desired word). Additionally, significant age-related differences are more readily found when working memory processes are taxed, resulting in greater cognitive resources. Older adults have been found to outperform younger adults in certain areas of message production and discourse, such as storytelling, while performing less well in tangential conversation (for example, discussing irrelevant family dynamics or past history, giving directions, or verbosity (Kemper & Kemtes, 2000)). Overall, older adults maintain exceptionally high language processing skills by relying on contextual features (or top-down processing, using their well-developed semantic and linguistic knowledge and listening to the prosody of speech.

Wisdom

Many of us believe that as we age and gain life experiences, we develop a deeper knowledge and understanding of our world, resulting in wisdom. Definitions of wisdom typically dictionary/wisdom), However, operationally defining the construct wisdom as well as developing reliable and valid methods for studying wisdom is actually quite difficult, which has resulted in mixed research findings. A review study by Sternberg (2005) highlights these mixed findings with views ranging from wisdom decreasing with age, to increasing with age, to remaining stable after a certain threshold (for example, early 20s). Grossman and colleagues found that despite declines in some fluid measures of intelligence, such as speed of processing and working mem- ory, older adults performed better than younger and middle-aged adults on assessments of wisdom. On the other hand, the Berlin Wisdom model (Baltes & Staudinger,

Mickler & Staudinger, 2008) posits that wisdom appears to plateau around age 20 and remains fairly stable until declining at age 75. Future research should focus on developing a standard definition of wisdom in addition to valid measures because this would provide a better understanding of how wisdom changes across the life span.

Expertise

Expertise is defined as having a high level of skill or know!-edge in a particular area and reflects problem solving, reasoning, and memory. Overall, research investigating the role of experience and expertise on older adult performance has found a pattern of maintenance. Several studies have shown the buffering effects of expertise in areas such as typing, playing the piano, and playing chess. These studies demonstrate the concept of plasticity in cognitive processing and warrant further research addressing"how" and"what" components of skill and knowledge acquisition are responsible for developing expertise. Research is also needed to further understand how expertise functions as a potential buffer or moderator of age-related differences.

Additional Cognitive Processes

Implicit and Explicit Processing

Implicit and explicit processing are two types of cognitive processes used to learn (or transfer) information from short-term to long-term memory and to retrieve information from long-term to short-term memory. Implicit processing is unintentional, occurs without awareness, and is effortless, requiring minimal cognitive resources. Explicit processing is intentional, occurs with awareness, and is effortful, requiring moderate to substantial cognitive resources.

To illustrate both processes, imagine learning the lyrics to a song. You could learn the words to a song implicitly by listening to a song on the radio multiple times. Over time you would, without awareness, have learned the lyrics to the song. Or you could use explicit processing by deliberately practicing the song lyrics every night for 30 minutes. Other examples of tasks that use implicit processing include driving a familiar route, playing an instrument, or reciting the alphabet. Driving in an unfamiliar location, learning to play an instrument, or reciting the alphabet backward would require effortful and explicit processing. In general, novel task require explicit processing, and tasks that have been learned or practiced repeatedly switch to implicit processing.

Overall, research has found age-related differences in tasks and activities that require explicit processing and little to no age-related differences for tasks and activities that require implicit processing. Focusing on familiar tasks during rehabilitative interventions may improve outcomes as they rely more on implicit versus explicit processing. For example, practicing the individual's actual dressing and grooming routine may be more beneficial than manufacturing novel tasks or activities that only simulate these tasks.

Intellectual Abilities

Conceptually, intelligence comprises two types of abilities: Huid intelligence and crystallized intelligence. Flud intelligence is the ability to use abstract reasoning, flexibly shift one's mental set, and initiate and complete purposeful action. It includes the creative and flexible thinking required in novel situations and can be directly affected by physiological structure changes. Crystallized intelligence is the accumulation of knowledge, experience, and acculturation that is highly representative of individual differences.

Research findings suggest several trends with regard to intelligence over the life course. Intellectual ability, taken as a whole, remains relatively stable and constant throughout the life span. However, the components of intelligence, fluid and crystallized, change with age. Specifically, fluid intelligence exhibits an interesting pattern in which ability increases until age 40 to 50, is maintained until one's 60s and 70s and then begins to decline. This pattern of change is of interest because it does not reflect a general linear decline across cognitive abilities that is reflected in earlier studies of cognitive aging that used cross-sectional research designs. For example, across the following cognitive processes fund crystallized, numeric facility and perceptual speed tend to decline first, followed by inductive reasoning, spatial orientation, and verbal memory around age 67. Crystallized intelligence, on the other hand, increases throughout the life span and is relatively well maintained in old age. For example, verbal ability is well preserved across the life span and begins to demonstrate age-related declines around age 81. Overall intellectual abilities remain relatively stable across the life span as the declines evident with fluid abilities are balanced by the gains found in crystallized abilities.

It is important to briefly mention what researchers have termed terminal decline, which is a significant decline in cognitive functioning that occurs several years prior to death for some individuals. Terminal decline can be due to neurological difficulties and also broader physiological changes that occur as one approaches death. More research is needed to better understand the underlying mechanisms and how terminal decline may affect older adults' functioning.

Theories Of Cognitive Aging

Several theories have emerged attempting to explain why and how certain cognitive processes change and decline across the life span, We elaborate here on four theories of cognitive aging that have received the most investigation: (1) speed of processing, (2) working memory, (3) inhibition, and (4) sensory functioning known as the"common cause" hypothesis.

Speed of Processing Theory

The speed of processing theory identifies generalized slowing as an explanation for age effects on cognition over the life span. This theory suggests that age-related differences between younger and older adults on cognitive tasks can be attributed to a generalized slowing or decreased speed at which individuals are able to process information. It is theorized that this decrease in processing speed has an impact on performance across a wide range of cognitive processes and tasks, such as attention, working memory, and decision-making.

Initially, researchers theorized generalized slowing ac- counted for decline across all cognitive processes and that all cognitive processes declined at the same rate (eig, Birren,

1965; Salthouse, 1990, 1996). Furthermore, older adult per- formance could be predicted by knowing how younger adults perform because the difference was only quantitative (no qualitative) in nature, with older adults performing x time: slower than younger adults. The implications of generalized slowing are tremendous for researchers, clinicians, and individuals. If one assumes this "strong version" of generalized slowing is correct, the implication is that cognitive aging occurs within a biological-based model, and associated declines are inevitable; thus, the role of individual differences, intervention, and plasticity would not be applicable.

Promoting Best Practice

Speed of Processing

The extent to which speed of processing accounts for age-related differences has been investigated extensively. Support has been found by Salthouse (1996), with 70 percent of age-related variance on cognitive task performance explained by speed of processing. However, other researchers have identified different results when analyzing this data, resulting in only 7 to 29 percent of variance explained. Additionally, several studies have found that speed of processing alone is not sufficient to explain all of the age-related differences in task performance. Wasylyshyn and colleagues controlled for processing speed at baseline but still found significant age-related differences in higher level cognitive functioning; therefore, speed of processing alone did not fully explain the age-related differences between younger and older adults.

On the basis of these findings, proponents of this view advocate for a modified version of generalized slowing that is either task-specific or process-specific. The implications of a modified theory of generalized slowing are quite different from the original conceptualization and allow for differential rates of change within and across cognitive processes: Additionally, this modified version of generalized slowing takes into account the role of individual differences, intervention, and plasticity.

Working Memory

Another domain that has been identified as being responsible for age-related cognitive decline is working memory. As discussed earlier, working memory is the online processing or active manipulation of information required during mental tasks. For example, adding up the total cost of groceries requires both storing and maintaining information while simultaneously calculating the total cost. It is hypothesized that working memory declines are in part responsible for explaining age-related changes in cognitive processing between younger and older adults. Hartley and colleagues found that working memory independently explained age-related changes in cognitive task performance. Other researchers report a near-perfect association between working memory and executive functioning while also noting that almost all of the age effects on episodic memory are removed when accounting for working memory. Additional support for this theory has been found with neuroimaging studies attributing age differences in brain activation during a cognitive task to individual variations in working memory span.

Inhibition

Another theory of cognitive aging is inhibition. According to Hasher and Zacks, when processing information, difficulties filtering or actively ignoring irrelevant information become problematic with age. Inefficient filtering can overwhelm the cognitive system and make it difficult to prioritize and process information. It is hypothesized that older adults, compared with younger adults, have greater difficulty inhibiting distracting or irrelevant information, resulting in older adults performing less well than younger adults.

Researchers supporting the work of Hasher and Zacks have identified evidence that age-related effects on inhibitory control are responsible for cognitive aging. Fox example, in a reading with distraction activity, inhibitory control was the significant predictor of performance on cognitive tasks. Compared with other theories of cognitive aging, the effect of age on inhibition has been found to be independent from declines in working memory or processing speed. Lustig, Hasher, and Tonev (2006) found that improvements can be made in older adults' performance on processing speed tests when the number of distractions is reduced. In addition to the behavioral evidence found using assessment tools (for example, interference tasks such as the Stroop task), neuroimaging evidence has supported the difficulty older adults have with inhibition during different memory tasks.

Interestingly, Healey, Campbell, and Hasner (2008) identified a potential benefit for older adults not engaging in inhibition processing. Specifically, if information is not filtered or actively ignored, it is available for later processing. For example, in a negative priming task, an individual is first asked to ignore an object (or word) and then later is asked to pay attention to the object (or word).

According to inhibition theory, responding to the object (or word) the second time should take longer. However, older adults' reaction time would not increase because they would not initially have inhibited the object (or word). Thus, compared with younger adults, older adults would experience less difficulty in completing this task. Common Cause Hypothesis

(Sensory Functioning)

Finally, Baltes and Lindenberger (1997) suggest a"common "cause" that is responsible for cognitive differences between younger and older adults. Sensory functioning, primarily measures of visual and auditory processing, have been proposed to explain age-related cognitive declines. Research has documented the visual and auditory sensory declines associated with aging. These declines in sensory functioning result in degraded (or poorer quality) information and are proposed to explain why older adults perform less well than younger adults on cognitive tasks.

According to the common cause hypothesis, older adults' cognitive processing (that is, decision-making, working memory, abstract thinking) take longer and or result in less accurate responses due to degraded information they have to use. For example, imagine listening to a presenter at a conference. You are sitting in the back of the room, and there seems to be a problem with the microphone. As a result, you only understand 60 percent of what the speaker is saying. This obviously is not due to your comprehension (or other cognitive processes) but to the degraded auditory information you are receiving.

Several studies have found that sensory functioning, including visual and auditory acuity, accounted for nearly all of the age-related variance in cognitive performance. Lin and colleagues also found that greater levels of hearing loss were significantly associated with multiple measures of cognition including global mental status, executive function, and memory. When sensory conditions were controlled, older adults and younger adults performed equally across several cognitive tasks, which further strengthens the idea that sensory functioning is integral in cognitive processing.

Empirical support for each of these cognitive aging theories has been found. However, exclusive support for one theory over others has not been found because these theories may be complementary rather than mutually exclusive. Further research is needed to understand how these four theories independently and inter-dependently explain age-related differences across cognitive processes. It also is important to understand why and how certain cogni- tive processes exhibit maintenance or gains across the life span. To date, explanatory theories have not been proposed. Optimizing Cognitive Aging and Health

Positive aging literature points to three specific areas to maximize one's intellectual and cognitive abilities throughout the life span: physical activity (for example, aerobic activity, strengthening, balance, and flexibility activity, mentally stimulating activities, and social engagement (Hertzog, Kramer, Wilson, & Lindenberger, 2008; Kramer et al., 2006; see figure 7 to 2). Cardiovascular fitness and training, which describes how the body consumes and moves oxygen throughout the body, has been associated with optimizing cognitive health by improving overall health (for example, reducing cardiovascular disease) and potentially delaying or slowing cognitive changes. Several neural protective physiological changes are associated with cardiovascular training including increased cerebral flow, which will provide better supply of oxygen and nutrients to brain tissue; increased level of brain-derived neurotropic factor, which is an important neural growth hormone; increased levels of insulin-resistant growth factor-1, which is another important growth factor in adults; and increased brain volume (especially white matter or cortical tissue) in frontal, temporal, and parietal lobes. Research has found individuals who have a greater level of fitness at baseline are found to demonstrate lower levels of cognitive decline into older age, additionally, aerobic training programs have been identified as effective in improving levels of executive function and inhibition on a decision-making test. Through regular interactions during the rehabilitation process, therapists can integrate these types of activities into the plan of care as well as educate the patient on continuing these aspects of cognitive enrichment following formal rehabilitation. Participating in mentally stimulating and novel activities can include increasing the difficulty of cognitive tasks during therapy and educating patients to challenge themselves at home with new and unfamiliar tasks, such as learning a new language or activity. To be considered mentally stimulating, tasks should be novel and mentally challenging, as new learn- ing facilitates neural growth, development, and plasticity. For example, if an individual completed the newspaper's crossword puzzle every day for 15 years crossword puzzles would not be considered a mentally stimulating activity because it is familiar and well practiced. Maintaining an active lifestyle that includes regular exercise promotes healthy cognitive functioning and serves as a neuroprotective buffer. Finally, promoting social engagement can be achieved simply by conducting therapy interventions in a gym setting rather than individually in a private room (as appropriate) as well as suggesting different activities for the patient throughout the day. Discussing the importance of social engagement once a patient returns is also important. Understanding an individual's daily routine and social support may highlight areas in which additional social engagement is needed. Including these additional principles routinely into regular rehabilitation sessions as well as providing comprehensive education for the patient may greatly facilitate healthy cognitive aging.

Cognitive reserve is the amount of resources left over and available after an individual engages in a task, which uses up some of the capacity. Many physiological functions have a residual or reserve capacity. For example, heart rate reserve is the difference between one's maximum heart rate and current heart rate, whereas physical reserve capacity is the difference between one's maximal ability and current level of functioning. Individuals can improve and build these reserves.

Just like lifting weights can improve strength, mentally stimulating activities can protect one's cognitive abilities by building a cognitive reserve. If an individual can build a large cognitive reserve, there is less chance that activities of daily living will surpass available resources. More information about cognitive reserve is located in Chapter 25.

Individuals who are engaged in regular social activities have a tendency to have lower rate of cognitive decline over the life span. Social engagement can range from regular contact with friends and family through visits at home to regularly scheduled lunches, to participation in hobbies and leisure activities with others, such as fitness classes at the com munity recreation center or a swimming club. Additionally, it has been identified that social isolation and lack of perceived social support can have detrimental effects on psychological well-being, including development of depressive symptoms, as well as a more rapid cognitive decline with age (Fiori, Smith, & Antonucci, Hertzog et al., Uchino,

Civic Engagement and Cognition

Civic engagement (for example, volunteerism) and lifelong learning can be used to assist older adults in maintaining high levels of social engagement and quality interaction. Wilson (2001)

identifies several motivations for support of lifelong learning:

updating of knowledge, skills, and abilities needed to keep allowing older adults to maintain purpose after retirement;

facilitating successful aging through education of disease prevention and good self-care and health practices.

Volunteering is an avenue used for many purposes depending on the individual and can be defined as "an activity undertaken by an individual that is uncoerced, unpaid, structured by an organization and directed toward a community concern"

. Although it is clear that maintaining a physically active and mentally stimulating lifestyle with regular social interaction assists in facilitating healthy cognitive aging, further research is needed in each of these areas to better understand the direct impact and underlying mechanisms responsible. Additionally, it would be beneficial to identify potential barriers or facilitators, such as personality traits, demographic characteristics, or external resources (for example, social support, financial resources) for participating and adopting physically, mentally, and socially engaging health behaviors throughout the life span.

Summary

Collectively examining the cognitive aging literature, several interesting patterns emerge that reflect a framework of gains, declines, and stability. Two intertwined factors for understanding these different trajectories include the cognitive resources required and the complexity of the task, which can range from novel to familiar. These results also highlight the multidirectionality and multidimensionality found within cognitive aging. However, there are many unanswered questions in understanding why and how certain cognitive processes decline while other processes remain stable or improve through out the life span.

One of the more difficult challenges faced by researchers, clinicians, and policy makers is how best to interpret and translate research findings to real-world situations, clinical protocols, and policies. As discussed earlier, lab-based findings are informative for understanding cognitive aging and testing specific theories. However, an important question is how relevant are these results for older adults in their day-to-day lives.

Does it make a difference whether it takes older adults 3 to 5 seconds longer to answer the phone? What about 3 to 5 seconds while driving and needing to stop quickly? These two examples highlight the complexities in translating basic research findings to real-world situations and clinical practice.

Understanding the complex pattern of cognitive aging can facilitate the development and implementation of training programs and interventions. Organizations and individuals in management positions could use this information to develop appropriate training programs that facilitate older adult learning, selection procedures that do not discriminate against older adults, and promotion systems that are fair. Policy makers are in a unique position to use cognitive aging research findings to promote funding for additional research and enact legislation that supports and accommodates individuals as they age. Mental health, medical, and rehabilitation professionals can greatly benefit from this information as it applies to treating and providing services to older adults.

In the rehabilitative setting, clinicians can use this information to either simplify or provide more challenging tasks for patients.

The population of aging adults is unique and requires a thorough understanding of the life span including healthy cognitive aging. Additionally, we must understand the intricate relationships between cognition and everyday function as well as being able to interpret relevant findings from the current literature to best translate this information from the laboratory to real-world and or clinical settings.

Case Study

Mrs. Elaine Thomas is a 65-year-old who lives alone in a single-story condominium located in a suburban region. She has two adult children, one of whom lives within 15 minutes; the other lives out of state. Mrs. Thomas recently retired from her job as a second-grade teacher. She is very independent and does not have any serious chronic health conditions.

Although she has prepared financially for her retirement, she doesn't know exactly how she should spend her time. She wants to remain physically and mentally active and engaged. She does crossword puzzles, swims 3 times a week, and socializes with friends and family at least once a month.

Questions

1. Do Mrs. Thomas's children have cause for concern? 2. Please provide rationale for your answer.

3. On the basis of her presentation, what recommendations would you have for Mrs. Thomas and her family? critical Thinking Questions

1. What are the methodological concerns facing researchers in adult development and aging? What are the strengths and limitations of cross-sectional and longitudinal research designs?

2. Discuss the importance of using the four tenets to study and understand cognitive aging.

3. Describe the normal effects of age on memory. How might these changes affect the treatment approach in a rehabilitative setting?

4. Discuss how older adults remain functionally independent in a community-dwelling environment.

5. How would you describe the process of healthy cognitive aging to someone who is not familiar with the research literature?

6. Discuss two basic theories or mechanisms that have been proposed to account for age-related cognitive decline. Are these theories (or mechanisms) mutually exclusive? Why or why not?

7, What advice would you give to a middle-aged individual (or anyone for that matter) wanting to maintain an optimal level of cognitive functioning as he or she ages?