Even light exercise could help slow cognitive decline in people at risk of Alzheimer's

The researchers found:

• In EXERT participants, cognitive function remained stable over 12 months in both low and moderate-high intensity exercise groups.
• Both forms of exercise were associated with significantly less cognitive decline over 12 months when compared to individuals who were not involved in the exercise study.
• Both EXERT exercise groups tended to show less brain volume loss over 12 months, including in the prefrontal cortex.

Individuals with amnestic mild cognitive impairment, a condition characterized by memory complaints and objective memory decline, are at high risk of developing Alzheimer's dementia, with approximately 16% of people with this condition progressing to Alzheimer's each year.

"This is a critical time to intervene in this population, because they don't have dementia yet, but are at a very high risk," said Aladdin Shadyab, Ph.D., M.P.H., lead author of one of the new papers and associate professor at the UC San Diego Herbert Wertheim School of Public Health and Human Longevity Science and School of Medicine. "Together, these findings show us that even low intensity exercise may slow cognitive decline in at-risk older adults."

While previous studies have suggested that exercise may be beneficial for cognitive health, the evidence has been mixed, and large, well-designed studies are needed to fully understand the potential benefits of exercise for older adults with mild cognitive impairment. The EXERT study, coordinated by the Alzheimer's Disease Cooperative Study (ADCS) at UC San Diego, in partnership with Wake Forest University School of Medicine, fills this gap.

"EXERT was one of the first large clinical trials of exercise that partnered with the YMCA and its trainers to bring the intervention closer to home for research participants," said Howard Feldman, M.D., ADCS director. "This approach brings us one step closer to its implementation in the community."

The ADCS was formed in 1991 under a cooperative agreement between the National Institute on Aging and UC San Diego and is one of the key initiatives for Alzheimer's research supported by the federal government, addressing treatments for both cognitive and behavioral symptoms of Alzheimer's.

"There's an urgent need to identify effective and feasible ways to prevent and treat Alzheimer's dementia, and UC San Diego has been a leader in this field for many years," added Feldman, who is also a professor in the Department of Neurosciences at UC San Diego School of Medicine.

EXERT included nearly 300 sedentary older adults with mild cognitive impairment who were randomly assigned to either moderate-high intensity aerobic training or lower-intensity stretching, balance and range of motion activities. Participants completed their assigned exercise 3-4 times per week for 12 months under the supervision of a YMCA trainer, and the study also included regular assessments of cognitive function and brain volume.

"EXERT is a landmark study because it's the largest rigorous trial of exercise ever conducted in adults with mild cognitive impairment," said Laura Baker, Ph.D., principal investigator of the EXERT study and professor of gerontology and geriatric medicine at Wake Forest University School of Medicine. "Exercise has well-documented benefits to nearly every aspect of human health, but we're still unlocking the full potential of exercise as medicine for older adults with memory problems.

Though the researchers expected to see further cognitive decline in EXERT participants, they actually found that cognitive function remained stable for both exercise groups over the course of the study. This suggests that both lower and higher intensity exercise could slow cognitive decline. Another possible explanation for the results is that participating in research itself, regardless of the treatment, may offer protection against cognitive decline due to the intellectual and social stimulation involved.

Overall, the findings of both studies taken together suggest that exercise may be a promising, safe, and feasible strategy to promote brain health and prevent continued cognitive decline for older adults with mild cognitive impairment.

"While there's still a lot to learn, these findings show that regular intensity exercise, even at low intensity, could go a long way toward helping older adults slow or delay cognitive decline, and this is promising news for those who are at high risk for dementia," added Shadyab.