Exercise at midlife may not help maintain long-term cognitive function

Results from a 30-year cohort study demonstrated that physical activity in midlife was not linked to cognitive fitness later in life, according to findings published in Journal of Alzheimer’s Disease.

Perspective from Carol F. Lippa, MD

Although physical activity may not help prevent the onset of dementia and Alzheimer’s disease, the results showed that activity levels among participants in later years was associated with high cognitive function 2 years later, suggesting that exercise may help to maintain short-term cognition among older adults.

“This study reminds us that physical activity has all sorts of benefits for people, including promoting cardiovascular health, managing optimal weight levels and maintaining bone and muscle mass,” Alden L. Gross, PhD, assistant professor in the department of epidemiology at Johns Hopkins University Bloomberg School of Public Health, said in a press release. “Unfortunately, it is too early for us to say the same about exercise and Alzheimer’s, especially as a possible long-term preventive measure.”

Prior research has shown that physical activity may help prevent Alzheimer’s disease, but these studies have rarely been conducted over a long period of time. Gross and colleagues examined data from the Johns Hopkins Precursors study, which enrolled medical students from 1948 to 1964 and asked questions annually about overall health, to assess whether physical activity in midlife is associated with late-life cognition and dementia. Using responses from 646 participants regarding exercise, physical activity and physical limitations, they calculated metabolic equivalents (MET h/day) and exercise from 1978 to the present. Researchers administered cognitive tests in 2008 and scored dementia through 2011.

The investigators found that no physical activity measure in midlife was linked to late-life cognitive fitness or onset of dementia. In addition, they found no association between patterns of change in physical activity levels over a person’s life span and cognitive health. However, MET h/day (=0.007, 95% CI, 0.002-0.013) and regular exercise (=0.357, 95% CI, 0.202-0.513) in 2006 were linked to better cognition in 2008, supporting previous studies that found exercise may contribute to cognitive fitness in the short term.

“We still need to focus on causes and mechanisms of Alzheimer's and dementia, since we don't yet know which preventive measures may or may not work,” Gross said in the release. “The goal for researchers is to identify factors that may help older people maintain their cognitive function into their later years. More long-term studies like the Precursors study are needed.” – by Savannah Demko

Disclosures: Healio Internal Medicine was unable to confirm relevant disclosures.

Perspective

Carol F. Lippa, MD

The results of this study conflict with other studies, particularly a large twin study published in 2016. The 2016 study involved physical activity data in twins in their 40s and cognitive abilities 25 years later. They compared cognitive ability between the physically active twin with the inactive twin. They found that fitness in midlife is associated with better cognitive status. However, they focused on the benefit of moderate exercise, and did not find that more exercise (extreme exercise) was better than moderate exercise. The subject population in the Hopkins study comprised medical students, which is questionably a similarly homogeneous population. Also, it isn’t clear if the Hopkins study looked at the degree of exercise (ie, assuming more is better). My bottom line remains to recommend moderate daily exercise, starting by middle age.

Carol F. Lippa, MD

Director, Cognitive Disorders and Comprehensive Alzheimer’s Disease Center

Vickie and Jack Farber Institute for Neuroscience

Thomas Jefferson University Hospital

Disclosures: Lippa reports no relevant financial disclosures.

Sources/Disclosures

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Source:

Gross AL, et al. J Alzheimers Dis. 2017;doi:10.3233/JAD-170290.