Dear Doctors: I retired last fall, and while I do enjoy the free time, I’ve become worried that the loss of mental stimulus will affect my memory. My husband says he heard about a study that showed being physically active helps your memory. Do you know if that’s true?
Dear Reader: The idea that regular exercise has a beneficial effect on memory and cognition has been with us for decades, if not centuries. The current body of research dates back to the 1950s, with most of the studies concluding that, yes, staying physically active is very good for the brain. This fascinating connection, which we have written about several times over the years, continues to generate new letters, like yours. It also continues to fuel a steady stream of new research.
A study published last year in the Journal of Alzheimer's Disease looked at the potential link between exercise and brain volume. This is a significant metric, as a decrease in brain volume is one of the factors observed in people undergoing cognitive decline, including in neurodegenerative diseases such as Alzheimer’s. The study examined the brain scans of more than 10,000 women and men ranging in age from 18 to 97 years old. The data showed that people who spent at least 25 minutes per week doing moderate physical exercise -- such as running, cycling, swimming and walking -- had larger brain volume than those who were sedentary. It’s important to note this held true across all age groups.
Another recent study found that people engaging in moderate or vigorous daily exercise performed better on cognitive tests than did those who were not physically active. In this study, the benefits were observed even in people who did as little as 10 minutes of exercise per day. And for anyone frustrated by the kind of memory lapse in which the word you want is on the tip of your tongue but you can’t quite get it, physical fitness may play a role. Another British study, published in 2018, found a strong connection between aerobic fitness and the ability to readily remember the words the participants wanted.
Interestingly, researchers are also looking at the reverse -- that is, whether or not the chemical compounds produced by the body during exercise might be harnessed for use as treatments for cognitive issues. For instance, when we exercise, our muscles produce a hormone known as irisin, which is believed to play a role in preserving cognitive health. Now, several mouse studies have pointed to a connection between blood levels of irisin and improved memory. In one of the studies, blocking irisin production in the mice led to measurable cognitive decline. In a different study, increasing blood levels of irisin led to improvements in memory and cognition.
While the mechanisms behind the beneficial effects of exercise on brain chemistry, memory and cognition have yet to be fully understood, the positive results are very clear. And if anyone needs a bit more persuading, don’t forget that regular exercise helps lower blood pressure, improves glucose control, bolsters mood, aids in bone strength and helps in maintaining a healthful weight.
(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
