FEBRUARY 2007

EVIDENCE CONTINUES to mount that keeping fit may help protect your brain. Scottish and French researchers, in two separate studies published in the journal Neurology, recently concluded that people with a greater degree of lifelong fitness are more likely to have better cognitive function into old age.

In the Scottish study, 460 surviving participants of the 1932 Scottish Mental Survey were given the same general cognitive test at ages 11 and 79. Subjects also were tested on their grip strength, six-meter walk time and lung function. Results showed a positive correlation between physical fitness and improved cognitive aging.

“Intervention studies aimed at making older people fitter are good candidates to improve cognitive aging,” concluded lead researcher Ian J. Deary, PhD, of the University of Edinburgh.

In the French study, researchers at Toulouse University Hospital also looked at the fitness-cognition connection and found that the higher the subjects’ Body Mass Index (BMI), the lower their scores on cognitive performance tests, both at the beginning of the study and at a five-year follow-up. The study compared cognitive function data on 2,223 subjects, ages 32 to 62 at the beginning of the study. Participants were tested on their ability to learn and retain lists of words, substitute symbols and maintain attention.

After adjusting for physical, psychosocial and other covariables, researchers found that participants with a higher BMI had lower cognitive scores. In fact, a higher BMI at the beginning of the study was associated with even higher cognitive decline at follow-up, suggesting that the earlier in life people get fit, the better for their long-term cognitive health.

American scientists concur. Research presented at the American Academy of Neurology meeting last year also suggests that “middle-aged spread” may be linked to a greater risk of Alzheimer’s disease (see the July 2006 Healthletter). Rachel A. Whitmer, PhD, of Kaiser Permanente in Oakland and colleagues compared the body fat measurements of 8,776 men and women, ages 40 to 45, and found a statistically significant link between flab and subjects’ rate of developing Alzheimer’s disease over an average of 23 years later.

Those findings support a previous Whitmer-led study, published in 2005 in the British Medical Journal, that looked at 10,276 men and women over a 27-year span. In that study, obese people had a 74% increased risk of dementia and overweight subjects had a 35% greater risk, compared to those with normal BMI. Those with the greatest skinfold thickness, as measured by calipers, had a 59-72% greater risk of dementia.

Though researchers stopped short of saying a leaner waistline can prevent cognitive decline, the results add yet another reason to trade your rocking chair for walking shoes.