A new study reports that the more physically fit you are when youre younger, the more likely you are to keep your brain sharp as you get older. But theres also good news for those who slacked off in their youth: Even starting to get more fit now might still improve your cognitive health.
There is growing evidence that physical exercise can benefit cognitive function in middle-aged and older adults, possibly through improved cardio- and cerebro-vascular health, says Tammy Scott, PhD, a scientist at Tufts HNRCA Nutrition and Neurocognition Laboratory.
THEN AND NOW: The new findings, published in Neurology, used data from the CARDIA (Coronary Artery Risk Development in Young Adults) study, begun in 1985-86. Participants, originally ages 18 to 30, were tested for blood pressure, cholesterol levels and other measures, and also walked at an increasingly fast pace on a treadmill until they couldnt continue. The young adults could stick with the treadmill test an average of 10 minutes.
Some 20 years later, scientists recruited 2,747 of the original participants, now ages 43 to 54. Asked to repeat the treadmill test, the middle-aged volunteers managed an average of only seven minutes. Although many had declined in aerobic fitness since the first test, others maintained their baseline levels-with a few actually improving on their younger selves.
Next, 25 years after the CARDIA study, participants were given a battery of cognitive tests, which had not been part of the original experiment. These included remembering lists of words, substituting symbols for digits as instructed, and distinguishing colors from text (so, for example, when shown the word green written in red letters, they had to identify the red color of the ink rather than the color word green).
FITTER AND SHARPER: Ultimately, a total of 1,957 people completed both treadmill tests and the cognitive tests over the 25-year span. Those who had been fitter as young adults generally scored better on the cognitive tests in middle age. Each additional minute that a participant had been able to last on the original treadmill measurement was associated with one extra recalled word in the memory tests and one fewer color-text mistake, as well as faster scores on the digit-symbol substitution. Those differences declined somewhat after adjusting for demographic factors. But that early-fitness edge represents the equivalent of about one years less mental aging.
One years difference in middle age might not sound like much. But David R. Jacobs Jr., PhD, of the University of Minnesota, corresponding author of the study, said such differences might be magnified in later years. Other studies have found that, among people ages 65-70, a one-word difference in recall tests translated into a nearly 20% difference in relative risk of dementia.
If you were a couch potato as a young adult, however, the study also had a glimmer of good news: The small group of participants who maintained or actually improved their fitness from the original treadmill testing scored better on the cognitive assessment than those whose fitness had declined or stayed the same.
Its a clich, but it really is never too late to start exercising, Jacobs said. The lesson is that people need to be moving throughout their lives.