The Body–Mind Connection in Aging and Dementia

Abstract

Aging is associated with well-known changes affecting functions for all organisms. Research in Alzheimer’s Disease (AD) and dementia has logically focused on the brain and especially measurements of cognitive function, along with increasingly sophisticated neuro-imaging and biochemical measures. This focus has resulted in a seemingly endless stream of prospects for identifying early features of AD through sophisticated tests of cognition, cerebrospinal fluid biomarkers, and advanced neuroimaging. The paper in this edition of JAGS by Wilkins, et. al., (1) adds to our growing appreciation that impairments in physical function, which may be much easier than cognitive function to measure, seem to precede clinical onset of AD. While Wilkins’ findings cannot show whether impairments in the brains of patients with AD contribute to their declining physical function or whether loss of physical function contributes to the development of cognitive decline, this study does confirm that mind and body are inextricably linked in aging and especially in the development of late-life dementia. Studies that demonstrate this mind-body association are typically set in longitudinal cohort studies of community-residing older persons who are free of dementia when first enrolled. By regularly following study subjects as they age, investigators can detect changes that are later associated with development of AD and related dementias. Wilkins et al observed that persons with impaired performance scores at baseline more rapidly developed AD than those who were not impaired. This finding that some people “just slow down” as they approach late life and often before they develop noticeable features of a dementia with an insidious onset like AD will not surprise experienced physicians who have provided regular care to patients over time. Nor will it surprise the many lay people who are challenged to care for parents surviving into their late 70s and beyond, facing increasing decline in physical function, and then manifesting signs of cognitive impairment with late life dementia. Indeed, the inter-connectedness of mind and body during aging is likely self-evident to lay and professional alike. As such, a key tenet of geriatrics is to provide care for the whole person, realizing there is no mind-body dichotomy, but rather linked functions of mind and body that determine an individual patient’s overall well being. If these findings are so self-evident, why then might the connection of physical impairment to future dementia be of interest to geriatrics and AD research? One interesting feature is that physical performance impairments (2) are not the only non-cognitive declines associated with future dementia. Added to global impairment are olfactory functional decline (3); central auditory dysfunction (4); visual spatial dysfunction (5); changes in regulation of pupillary response (6); and beat-to-beat variation in heart rate (7), among others. This constellation of changes in bodily functions begs the question: To what extent does a battery of non-cognitive measures have the potential to reliably detect AD before it becomes evident clinically? Although we do not currently have effective prevention or disease-altering treatments for AD, efforts to develop such treatments continue. Once we have them, being able to reliably target treatment to those most likely to benefit will be critical for feasible and cost-efficient treatment. Exploration of promising and easy-to-administer measures of cognitive and non-cognitive functions is likely a fruitful area for future research suggested by this and other recent publications. The other important implication of Wilkins’ finding that physical impairment often predates AD is more immediate and relates to our current efforts to prevent or delay onset of dementing disorders to as late in life as possible. It’s well known that physical impairment in old age is modifiable through rehabilitation and habitual physical activity programs involving aerobic and resistive exercises or through the everyday habit of just plain walking. And, it should not be too surprising then that habitual physical activity has emerged as the modifiable risk factor with the most evidence supporting its benefit in preventing or delaying onset of dementia or late-in-life cognitive decline. (8, 9, 10) While it’s self evident that habitual physical activity is never going to be 100% effective in preventing late life dementia, the public-health benefits of delaying onset of late life dementia will likely be considerable. I believe we can expect better and more evidence of the benefits of habitual physical activity in reducing the burden of AD and late life dementia in general over the next several years. The greater challenge will be finding ways to increase physical activity throughout sedentary societies and to promote behavior change at the individual level. The fact that “Alzheimer’s” or, as some used to say, “old timers’ disease” is among the most, if not the most dreaded consequences of living to a “ripe old age”, may be just the motivation our culture and individuals need to develop healthy exercise habits, like brisk daily walks, (8) as part of our daily routine.