Alzheimer’s disease (AD), the most common type of dementia, is characterized by a progressive deterioration of cognitive function that may lead to a decline in physical ability.

According to both animal and human research, physical activity can protect against the development of AD. It may also improve physical function and slow or prevent cognition loss in people who already have AD, but the meta-analyses exploring these potential benefits suffered from various methodological issues, such as combining randomized and nonrandomized controlled trials, combining trials examining AD with trials examining other types of dementia, including trials that combined physical exercise with other therapies, and not differentiating between types of exercise. These four issues are absent from the meta-analysis summarized here.

This meta-analysis of 21 randomized controlled trials assessed the effects of exercise (compared with no exercise) on 1,337 people with AD. Subgroup analyses were run for different types of exercise.

Four outcomes were examined:

• Cognitive function, as assessed via verbal fluency, Mini-Mental State Examination (MMSE), or Alzheimer’s Disease Assessment Scale–Cognitive Subscale (ADAS-Cog)
• Physical function, as assessed via walking speed, 6-Minute Walking Test (6MWT), Timed Up and Go test (TUG), Functional Reach Test (FRT), or Berg Balance Scale (BBS)
• Functional independence, as assessed via Barthel index or Katz index
• Neuropsychiatric symptoms, as assessed via neuropsychiatric inventory (NPI)

The average ages of the participants ranged from 69 to 90 years. The severity of AD ranged from very mild to very severe, with most participants being at a mild-to-moderate stage. The types of exercise were aerobic exercise (11 trials), resistance exercise (7), or a combination of both (12). The sessions lasted between 30 and 90 minutes, and most trials included 2–3 sessions per week. The trials lasted between 9 weeks and 9 months.

Exercise improved functional independence on the Barthel index, with a median difference of 8.4 points — a large effect size, since a Barthel index score can range from 0 to 20 points. Moreover, exercise improved 6MWT by 84 meters (276 feet), FRT by 3.7 centimeters (1.46 inches), BBS by 3.45 points, and neuropsychiatric symptoms (which are common in AD^[1]) by 3.9 points — all clinically meaningful effect sizes.

The benefit of exercise on MMSE (a measure of cognitive function) did not reach statistical significance in the overall analysis. In the subgroup analyses based on exercise type, however, aerobic exercise improved MMSE to a clinically meaningful degree.

In most of the analyses, there was a moderate or high level of heterogeneity. With that said, no publication bias was found, and the overall methodological quality of the included trials was moderate.

Other meta-analyses also found that aerobic exercise could improve cognitive function in people with AD.^[2][3][4]

Likewise, other meta-analyses also found that exercise improved functional independence and physical function in people with AD: a 2014 meta-analysis found that exercise improved activities of daily living and physical function,^[6] and similarly, a 2015 meta-analysis found that physiotherapy improved activities of daily living and various measures of physical function — including 6MWT, BBS, and TUG.^[7]

A 2015 Cochrane review did not find clear evidence that exercise alleviated the neuropsychiatric symptoms of older people with dementia, but this conclusion was based on only 1 trial.^[8] In contrast, 5 of the 7 trials investigated in a 2020 systematic review supported the benefits of exercise on the neuropsychiatric symptoms of older people with AD.^[9]

Overall, the available evidence suggests that exercise can improve physical function, functional independence, and neuropsychiatric symptoms in people with AD. Also, aerobic exercise may improve cognitive function to a small, but clinically relevant, degree.

Benefits of exercise in Alzheimer’s disease