Study: Exercise has no effect on dementia

Moderate to high-intensity exercise may improve physical fitness for dementia patients, but it does not improve, and may even worsen, cognitive impairments, according to anew study.

Published in the British Medical Journal, the study found moderate to high-intensity aerobic and strength training programs do not slow cognitive impairments for people with mild to moderate dementia, a disease that affects an estimated 47.5 million people globally, with 5.7 million Americans living with the most common form of the disease: Alzheimer's. Its conclusions contradict a widely popular belief that aerobic exercise and strength training might slow impairment associated with dementia.

"We'd all love to see a cure for dementia," Sarah Lamb, lead author of the study, says. "At the outset, it was unlikely this study would translate to large effects, at the very least we hoped it would improve cognitive and behavioral functions, but we didn't see improvement in those."

Researchers analyzed 494 dementia patients, with 329 patients assigned to an aerobic and strength training program in addition to usual care, and 165 assigned to just usual care. Participants underwent four months of physical exercise, personalized according to their fitness. Each of the 329 participants did two gym sessions a week lasting 60 to 90 minutes, involving exercise such as high-intensity cycling, strength training and using waist belts. They were also asked to do another hour of exercise each week at home during the four-month period.

Exercise does not improve dementia outcomes, and it may even make cognitive impairments worse for some patients, according to Lamb.

On average, by measuring the difference between participants, the study found those who completed the exercise program had worse cognitive scores than those who did not. The program made them physically fitter, but it did not slow down the progression of the disease. The negative effect of the exercise "is statistically significant, which is why we can't sweep it under the carpet," Lamb says.

Although moderate to high-intensity exercise improves physical fitness, in light of these findings, the researchers do not recommend it for dementia patients to manage cognitive impairment, functional impairment or behavioral disturbances including anxiety. But these findings should not deter people with dementia from doing any form of gentle activity or exercise, Lamb says.

"Gentle exercise is OK. It's not necessarily going to improve your cognitive status, but balanced evidence shows it is OK," Lamb says.

The study was funded by the National Institute for Health Research, which tests interventions that could be useful to the National Health Service.

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