The DASH diet, combined with exercise and calorie restriction, improved mental functioning by 30 percent in overweight adults with high blood pressure compared to those who didn't diet or exercise, researchers reported in Hypertension: Journal of the American Heart Association.

The DASH diet emphasizes eating low-fat dairy products, foods low in cholesterol and high in carbohydrates, and fruits and vegetables. The DASH diet comes from the Dietary Approaches to Stop Hypertension trial, conducted by the National Heart, Lung, and Blood Institute.

In this randomized trial, researchers examined the effects of diet and exercise on neurocognition (memory, attention, and ability to learn new material) in adults at risk for neurocognitive decline due to high blood pressure.

Researchers divided 124 men and women, average age 52, into three groups: the DASH diet combined with a behavioral weight management program including aerobic exercise and calorie restriction; the DASH diet alone; and usual care group with no diet or exercise. None were receiving medication for high blood pressure. Aerobic exercise consisted of a supervised workout, three times each week, for 30 minutes.

Researchers found that the diet and weight management group had:

• Improved cognitive function;
• Strikingly reduced systolic blood pressure by 16 millimeters of mercury (mmHg) and diastolic pressure by 10 mmHg over the four-month study period;
• Improved cardiovascular fitness and lower weight as well as reduced blood pressure compared to the other groups; and
• Lost an average of 19 pounds at the conclusion of the study. The other groups did not lose weight.

"This study has significant implications for slowing down or even reversing age-related cognitive deficits, which may even have greater impact among people vulnerable to develop dementia or Alzheimer's disease," said James Blumenthal, Ph.D., lead author of the study and professor of psychology and neuroscience in the Department of Psychiatry and Behavioral Sciences at Duke University Medical Center in Durham, N.C.

Participants had mild to moderate high blood pressure, with systolic blood pressures ranging from 130 mmHg to 159 mmHg, and diastolic pressures of 80 mmHg to 99 mmHg. The average blood pressure was 138/86 mmHg. Two-thirds were women. About 60 percent were Caucasian; about 39 percent were African American.

The body mass index (BMI) of the study population was 25 to 40 kg/m2; they were a minimum of 15 pounds overweight.

Researchers assessed mental functioning with a battery of neuropsychological tests, including Executive Function-Memory-Learning and Psychomotor Speed. The tests were given before and after the four-month treatment program.

Two strategies were used in the weight management program: a traditional approach with behavior modification, including portion control and techniques to improve eating patterns, and an approach called Appetite Awareness Training.

Appetite Awareness Training is a self-monitoring strategy developed to provide more specific guidelines regarding not just what to eat but how much to eat. Individuals learned to identify moderate hunger and fullness and to use these internal cues to guide their eating behavior.

"We taught people what to eat, when to eat, and how to eat," Blumenthal said. "Modifying lifestyles to achieve a healthy body weight, getting regular exercise, and eating properly not only have physical health benefits, but mental health benefits."

Researchers suggest future studies examine the effects of diet and exercise in adults at elevated risk for dementia.

The study was funded by the National Heart, Lung, and Blood Institute and the General Clinical Research Center, National Institutes of Health.

Co-authors are: Patrick Smith, M.A.; Michael Babyak, Ph.D.; Linda Craighead, Ph.D.; Kathleen Welsh-Bohmer, Ph.D.; Timothy Strauman, Ph.D.; and Andrew Sherwood, Ph.D.