COMMENTARY

Cognitive Health for an Aging Population

Laura A. Stokowski, RN, MS

Disclosures

November 16, 2009

In This Article

Public Health Implications

A convergence of social trends -- the burgeoning older segment of our population, mounting awareness and fear of dementia, and vanishing family caretaking networks -- is creating a "cognitive health crisis" of sorts. If life were a play, we would be well into the second act and beginning to sense that we weren't going to like the ending. True to their optimistic natures, however, many baby boomers are wondering whether an alternative ending might be possible.

Can the Course of Cognitive Health Be Altered?

We don't know for certain how much mileage we can really expect from the human brain. Is it possible to experience intact cognitive aging and preserve our cognitive abilities as we age? Some experts believe that it is, citing examples of elderly individuals who grow into old age without apparent cognitive decline, but few studies have attempted to define or explain "intact cognitive aging."[19] One thing we do know is that not all individuals show the same degree of cognitive decline with aging.[29] Researchers are starting to investigate the differences between those who age with and without cognitive decline in an attempt to identify the factors associated with successful cognitive aging.

In a prospective cohort study, Barnes and colleagues[32] evaluated cognitive function in older women, and compared women who maintained optimal cognitive function with women who demonstrated minor cognitive decline typically associated with aging.More than 9000 women with a mean age of 72 years at baseline were assessed with a modified Mini Mental State Examination at 6, 8, 10, and 15 years into the study. About 10% of the sample maintained optimal cognitive function into old age. Three distinct cognitive trajectories were apparent in study women over a 15-year period: (1) the "major decliners" (those who experienced significant cognitive decline); (2) the "minor decliners" (modest/typical cognitive decline); and (3) the "maintainers" (those with no decline on global cognitive function). Of note, compared with minor decliners, the cognitive maintainers reported fewer comorbid medical conditions such as diabetes and hypertension, were less likely to require assistance with activities of daily living, and had higher levels of social integration.

As part of the Health, Aging, and Body Composition (HealthABC) study, Yaffe and colleagues[23] evaluated the determinants of successful cognitive aging in a biracial cohort of men and women. In this group, 30% were maintainers, 53% were minor decliners, and 16% were major decliners. Factors that distinguished maintainers from decliners included:

  • White race;

  • Higher level of education/literacy;

  • Working or volunteering;

  • Not the caregiver of a spouse or child;

  • Living with someone at baseline;

  • Self-rated health good to excellent;

  • Consuming more than 1 alcoholic drink daily;

  • Moderate to vigorous weekly exercise;

  • Nonsmoker at baseline;

  • Lower BMI;

  • Lack of hypertension, diabetes, or stroke;

  • Lacking the APOE e4 allele; and

  • Lower levels of C-reactive protein, interleukin-6, and fasting glucose, and higher triglyceride levels.

The notion that the cognitive stimulation provided by typical everyday activities could maintain or improve cognitive agility the way that physical exercise can enhance cardiovascular function has obvious appeal. It is far more likely, though, that more novel and cognitively challenging activities will be required to maintain cognitive health.[33] Although a clear association exists between, for example, an engaged lifestyle and a reduced risk for dementia, this does not prove causality.[25] We don't know whether intelligence and educational level are protective in and of themselves, or whether individuals who are more literate and with greater educational attainment tend to adopt healthier, more intellectually challenging lifestyles.

Can people deliberately reduce their rate of cognitive decline or even reverse age-related cognitive decline? A study by Ball and colleagues[34] demonstrated that certain cognitive processes can be improved in the elderly through the use of intellectual exercises, supporting the theory that neural plasticity endures into old age. The ACTIVE (Advanced Cognitive Training for Independent and Vital Elderly) trial of more than 2800 elderly volunteers ages 65 to 94 years demonstrated that cognitive training in verbal episodic memory, reasoning, or speed-of-processing improved the abilities of normal elderly individuals to perform on multiple measures of the specific cognitive ability for which they were trained. Furthermore, the magnitude of cognitive gain by subjects was comparable to or greater than the magnitude of age-related decline, suggesting that cognitive intervention might even be able to reverse age-related decline.[34]

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