How Fitness Affects the Brain

Physical activity produces changes in areas of the brain also vulnerable to aging and Alzheimer's damage, such as the hippocampus, which plays an important role in learning, memory, and navigation.

Worldwide, 50 million people have dementia, and about 10 million are diagnosed each year, according to statistics from the World Health Organization. Physical activity has been linked in earlier studies to the slowing of cognitive decline and a decreased risk of dementia in old age, but few studies have examined the link between fitness in middle-age and dementia in very old age. Evidence on the long-term effects of fitness on brain structure and dementia risk is limited.

Mid-Life Fitness and Dementia Risk

To see if fitness levels in midlife affected dementia risk late life, researchers followed 191 Swedish women with an average age of 50, who were enrolled in the Prospective Population Study of Women (PPSW), for a total of 44 years.

The participants took a bicycle exercise test at the start of the study to measure their cardiovascular fitness. They also had their heart rate measured, blood pressure recorded, and perceived fatigue noted. They also underwent an electrocardiogram (ECG).

Six times through the course of the study, geriatric psychiatrists determined dementia based on information from neuropsychiatric examinations and interviews with patients. An official diagnosis was given if the participant had dementia according to both sources, or if it was evident from one source, and the other source spotted similar dementia symptoms.

Higher Fitness Equals Lower Dementia Risk

After the 44-year follow-up, women who had a high level of fitness at midlife, had a 5 percent risk of developing dementia compared to a 25 percent risk for women with medium fitness levels and a 23 percent risk for women with low fitness levels. Those who stopped exercising due to blood pressure, chest pain, or other cardiovascular problems, had a 45 percent higher risk of dementia. "This indicates that adverse cardiovascular processes might be going on in midlife that seem to increase the risk for dementia," according to the researchers.

Fitness Link

The association between high fitness levels and low dementia risk in this Swedish population suggests that improving fitness in midlife could be help delay or prevent dementia.

Further research is needed to determine if fitness can prevent dementia, and when specifically, during a person's lifetime, high cardiovascular fitness is essential. Fitness levels need to be measured more than once to take into account changes in fitness over time.

For more on exercise and the brain, read our story in The Waiting Room called The Exercise Effect. For other stories on exercise, visit our collection in Healthy Living. Look for another story on the best exercise for your condition in the April/May 2018 issue.