Diet, Exercise Can Improve Thinking
Study finds benefits for the mind, not just the body
MONDAY, March 8, 2010 (HealthDay News) -- A good diet and regular exercise may help the mind function better, a new study suggests.
"It looks like exercise and diet improve the range of cognitive function," said Patrick Smith, an intern in clinical neuropsychology and a member of a Duke University team reporting the finding online in the March 8 issue of Hypertension. "It helps executive function, learning and psychomotor speed."
The researchers followed 124 men and women with high blood pressure who were 52 and a minimum of 15 pounds overweight, on average.
Led by James Blumenthal, a professor of psychology and neuroscience at Duke, the study was designed primarily to determine the effect of diet and exercise on blood pressure and included people with mild to moderate high blood pressure.
The mental studies were included because "some previous data linked exercise and diet to better cognitive function," Smith said. The new results verified those findings, he noted.
A third of the participants went about eating and exercising as they usually did. Another third followed the DASH -- Dietary Approaches to Stop Hypertension -- diet, which emphasizes low-fat dairy products, fruits and vegetables, in combination with regular exercise. The final third were in a program that combined the DASH diet with a weight-management program and aerobic exercise.
Two strategies were used in the weight-management program: One centered on reducing portion size and changing habits, such as snacking. The other used an approach called appetite awareness training, which provides guidelines on how much to eat, not just what to eat.
Smith said the exercise part of the program wasn't drastic -- "workouts of 30 minutes three to four times a week, enough to put the heart up to 75 to 80 percent of its maximum rate."
To assess the effects on mental function, the participants were asked to do certain paper-and-pencil tests, such as crossing off specific digits on a page of numbers as quickly as possible.
The group that ate well and exercised regularly had an overall 30 percent improvement in mental function by the end of the four-month period, the researchers noted.
Physical activity does seem to have a direct effect on brain cells, Smith said. "There are neurochemical changes that happen with exercise, he said. There is increased production of brain-derived neurotrophic factor, which stimulates connection with other brain cells, he said, but also there is some evidence that it helps grow new brain cells."
And the combination of good eating and exercise also produced the expected physical advances. Diet-and-exercise participants lost an average of 19 pounds and lowered systolic blood pressure (the higher of the 120/80 reading) by 16 points and diastolic pressure by 10 points by the end of the four-month program.
Some experts believe the study has shortcomings, however. It's a well-done study, but one that has flaws, said Dr. Donald LaVan, a clinical associate professor of medicine at the University of Pennsylvania and a spokesman for the American Heart Association.
"Its entirely too small," LaVan said. "I would call it a keyhole study, suggestive but nothing definitive. Also, it did not have a control group to look at the effect of exercise alone. We need a bigger study with a longer duration and a control group for exercise alone."
Nothing in the study should deter anyone from exercising for the sake of the mind as well as the body, LaVan said.
"Exercise is great," he said. "But how much exercise itself contributes to mental function is not clear."
Advice on physical activity is given by the American Heart Association.