Last year, a study published in The Lancet found that nearly 3% of all Alzheimer's cases may be caused by lack of exercise [1]. In the United States alone, more than 1 million cases of Alzheimer’s may be due to physical inactivity. Still, nearly a third of Americans do not get enough exercise [2]. A new study adds to the evidence that exercise is good for your brain health—and you shouldn’t wait to get active.
Alzheimer's disease develops over decades, and many lifestyle choices in our 40s and 50s can affect our future risk. In 1968, researchers from the University of Gothenburg in Sweden tested the cardiovascular fitness of about 200 middle-aged women (ages 38 to 60) [3]. They measured how vigorously the women could ride on a standing bicycle and used the results to separate them into three fitness groups—low, medium, and high. From 1968 until 2012, the participants returned every 4–8 years to be tested for Alzheimer's and other types of dementia. The researchers found that women in the low fitness group were 41% more likely to develop dementia than those in the medium fitness group. However, women in the high fitness group were 88% less likely to develop dementia. And those who did develop Alzheimer’s or another dementia showed signs nine years later than those in the low fitness group.
The investigators caution that the sample size in the study was small. And this was an observational study, so they could not determine cause and effect. Fitness may also have a strong genetic component, and the researchers were unable to control for that. But, the study followed participants over 44 years, making it one of the longest studies to examine the effects of exercise on dementia risk. Despite the caveats, it does provide more evidence that cardiovascular fitness in our 40s and 50s can positively impact our future brain health.
How does exercise benefit the brain? The study showed that the participants in the high fitness group had a lower blood pressure than participants in the other groups. Mid-life hypertension is a risk factor for dementia. Other studies suggest that exercise may reduce cholesterol and inflammation and increase the release of brain-derived neurotrophic factor (BDNF), which is a protein that can protect our brain cells [4].
The World Health Organization recommends that adults get at least 150 minutes of moderate intensity aerobic exercise every week. No studies have proven that one type of exercise is better than another, so do what you enjoy! Brisk walking, jogging, cycling, or swimming—they can all benefit your brain health.
Nick McKeehan is a member of the ADDF's Aging and Alzheimer's Prevention program. He evaluates the scientific evidence for and against therapies to promote brain health and/or prevent Alzheimer's disease at our website CognitiveVitality.org and contributes regularly to the site's blog. Mr. McKeehan previously served as Chief Intern at Mid Atlantic Bio Angels (MABA) and was a research technician at Albert Einstein College of Medicine investigating repair capabilities of the brain. Mr. McKeehan received a bachelor of science degree in biology from Purdue University, where he was awarded a Howard Hughes Scholarship. He also writes about the biotechnology industry for 1st Pitch Life Science.
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