Cognitive Aging Progress in Understanding and Opportunities for Action (2015) / Chapter Skim
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3 Population-Based Information About Cognitive Aging
3 Population-Based Information About Cognitive Aging
Pages 75-108
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From page 75... ...
This chapter provides a brief overview of available population-based information about cognitive aging in the United States and discusses challenges and next steps in collecting, analyzing, and disseminating needed information that is not currently available. The chapter addresses the following questions: • How does a life-course perspective help inform the understanding of cognitive aging?
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From page 76... ...
.1 But, much less attention has been paid to population data on the less severe cognitive changes experienced by the majority of older adults -- changes that may affect important day-to-day activities, such as driving, making financial decisions, and managing medications. The resulting gaps in understanding of the larger picture of changes in cognition with aging underscore the need for population-based information on cognitive aging apart from moderate and severe cognitive impairment, dementia, and Alzheimer's disease.
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From page 77... ...
Examples include head or bodily trauma due to automobile crashes or military combat; major mental illnesses, such as affective disorders, substance abuse, or various psychoses; cerebro-vascular disease risk factors, such as uncontrolled hypertension and lipid disorders; toxic maternal exposures; and physiochemical exposures of hazardous occupations. All of these factors help explain the wide differences in cognitive status observed among individuals as they age.
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From page 78... ...
Other commonly used survey items ask respondents to name common objects, such as scissors; to name as many different animals as they can in a minute or two; to complete one or more partial sentences; to count backward from 100 by 7s; and to identify a missing number in a series of numbers. (See Box 2-1 in Chapter 2 for additional information about commonly used cognitive tests.)
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older Age: 32 to Medicare 84 years enrollee (MIDUS II) Includes nursing No Yes No Yes No home residents Measures No Yes Yes Yes Yes cognition directly Measures Yes Yes Yes Yes Yes awareness and perceptions about cognition Collects No Yes No Yes Yes information about sample person's cognition from a proxy/ informant continued
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managing housekeeping, finances, managing managing finances, medications managing medications Asks about Walking Walking, Walking, Walking, Walking, other physical and climbing climbing climbing climbing activity climbing stairs, stairs, stairs, stairs, limitations stairs crouching, stooping, kneeling, crouching, stooping, kneeling, lifting stooping, kneeling, lifting kneeling, lifting, lifting, getting getting up up from a from a chair chair Asks about race/ Yes Yes Yes Yes Yes ethnicity Asks about "ever served "ever served No Yes Yes veteran status in the in the military" military"
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(NHANES) Asks about Yes Yes Yes Yes Yes physical activity and exercise Asks about Yes Yes Yes Yes Yes cardiovascular risk factors: hypertension, diabetes, smoking Asks about No Yes Yes Yes Asks about social difficulty engagement participating in social activities or lack of such participation NOTES: Activities of daily living (ADLs)
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From page 82... ...
A brief overview of the information available about cognitive aging from these existing surveys and studies is presented below. Information is provided about three aspects of cognitive aging: cognitive status at a point in time, cognitive changes that occur in individuals as they age, and older adults' self-reported awareness and perceptions regarding these changes.
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. Figure 3-1 shows the average scores for all MIDUS II sample members on tests of two components of cognition: episodic memory, including immediate and delayed recall, and executive functioning.
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. As discussed earlier, analyses of data from many existing surveys and studies often focus on moderate and severe cognitive impairment, dementia, and Alzheimer's disease rather than on the less severe cognitive changes that are the topic of this Institute of Medicine report.
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FIGURE 3-3 Proportions of people age 65 and older with moderate or severe memory impairment versus no or mild memory impairment, Health and Retirement Study, United States, 2002. SOURCE: Adapted from FIFARS, 2004.3-3 Figure
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From page 86... ...
Yet some -- and perhaps many -- of the people who are shown as having no memory impairment or only mild memory impairment are likely to have experienced changes in memory and other cognitive functions that concern them and affect their day-to-day activities. The HRS findings on global cognition, including memory and other cognitive functions, are often reported in four categories: normal, plus three categories of cognitive impairment as defined for the particular study.
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From page 87... ...
Challenges and Opportunities for Point-in-Time Data Collection and Analysis In these surveys and studies, the focus on moderate and severe cognitive impairment and on probable and possible dementia undoubtedly reflects the high level of interest in dementia and dementia-related conditions among researchers, policy makers, and the public as well as the relatively lower level of interest to date in the less severe changes in cognition that are the focus of this report. People with less severe cognitive changes are variously categorized as having "normal cognitive function," "mild cognitive impairment," or "no dementia." The implications of these terms and categories are unclear with respect to cognitive abilities, impairments, and needs for information and assistance among the large number of adults so categorized.
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From page 88... ...
A study of 2,733 generally healthy men and women ages 70 to 79 years found that after 4 years, 36 percent of the sample members had maintained the same level of cognitive functioning, 48 percent had experienced a minor decline in cognitive functioning, and 16 percent had had a major decline (Yaffe et al., 2010)
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developed diagnosable mild cognitive impairment (MCI) , and 46 (3 percent)
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NOTE: MCI = mild cognitive impairment. The middle (black)
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. Others have been persuaded that subjective memory complaints indicate real cognitive impairment and may also predict future cognitive decline (see, e.g., Geerlings et al., 1999; Jonker et al., 1996, 2000)
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. Studies that include individuals with various levels of cognitive impairment have generally found a stronger association between subjective memory complaints and current cognitive status in individuals with no or very mild cognitive impairment than in individuals with more cognitive impairment (Lerner et al., 2015; Turvey et al., 2000)
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From page 93... ...
Age, level of education, and other socio-demographic factors have also been found to affect the association between subjective memory complaints and current cognitive status in older adults. For example, three studies found substantial associations between subjective memory complaints and scores on objective tests of cognition in the young-old sample members (individuals under ages 75 or 80 in the study samples)
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From page 94... ...
. Given the complexity of findings about the association of subjective memory complaints and current cognitive status based on objective cognitive tests, and given the still early stage of research on the association of subjective memory complaints and future cognitive impairment, caution is needed in the dissemination of findings from population-based surveys and studies that measure self-reported changes in cognition, such as BRFSS.
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From page 95... ...
, relatively little attention has been given to developing operational definitions that would allow for population-based estimates of the nature and extent of cognitive aging. As described in this chapter, findings about cognition from nationally representative surveys and studies, such as the HRS and NHATS, are often reported in categories that emphasize moderate and severe cognitive impairment and dementia.
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Operational definitions of cognitive aging will require, among other considerations, a standardized set of cognitive scales and tests. Many population studies use similar cognitive items and tap similar cognitive domains (such as memory, executive function, and orientation)
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Including Relevant Cognitive Tests and Survey Questions About Cognition As noted earlier, cognitive test results vary, depending on the specific test used. This is important because the cognitive tests used in existing population-based surveys and studies vary widely, in part because of the amount of time they allocate for cognitive assessment.
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From page 98... ...
includes questions about the areas in which a person needs the most help, such as whether the person's confusion or memory loss has interfered with his or her ability to work, volunteer, or engage in social activities. Likewise, the HRS and NHATS include questions that link cognitive decline with problems with various activities such as "being able to work familiar machines," "learning to use a new tool, appliance, or gadget," and "being able to follow a story in a book or on TV" (HRS, 2014b; NHATS, 2014b)
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From page 99... ...
Using Proxy Respondents and Responses Many existing population-based surveys and studies that measure cognition include questions that are asked of proxy respondents, who are usually family members and other informants, in addition to or instead of those questions for the older adults themselves. In some surveys, the proxy respondent answers questions only if the sample person is not able to, while in other surveys both the proxy respondent and the sample person answer the questions.
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How would incomplete participation rates, as well as information from proxy respondents, be handled? • What battery of cognitive tests should be included?
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Sales data for drugs or other products used for the prevention or management of cognitive impairment may provide useful insights into population and professional concerns. Similarly, it may be useful to monitor secondary effects of cognitive aging from public records, such as police reports of persons getting lost and automobile crash rates among older persons.
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Increased understanding about cognitive aging could help increase public awareness, answer questions and address concerns of older adults and their families, improve the information advice health care and financial professionals and others provide to their older patients and clients, and help public health agencies and other public and private organizations create effective programs to reduce cognitive impairment and improve cognitive health in older adults. RECOMMENDATION Recommendation 2: Collect and Disseminate Population-Based Data on Cognitive Aging The Centers for Disease Control and Prevention (CDC)
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2011. Spe cific subjective memory complaints in older persons may indicate poor cognitive function.
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Optional Impact of Cognitive Impairment Module. http://www.cdc.gov/ aging/pdf/impact_of_cognitive_impairment_ module.pdf (accessed February 26, 2015)
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2014. Prevalence and cognitive bases of subjective memory complaints in older adults: Evidence from a community sample.
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2015. Awareness of memory deficits in subjective cognitive decline, mild cognitive impairment, Alzheimer's disease and Parkinson's disease.
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Subjective memory complaints and cognitive impairment in older people. Dementia and Geriatric Cognitive Disorders 2(5-6)
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2006b. Improving measurement in health education and health behavior research us ing item response modeling: Comparison with the classical test theory approach.
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