CHICAGO – An active lifestyle positively influences brain volume in older adults with or without Alzheimer’s disease, a magnetic resonance imaging study revealed.
Among 876 individuals, the average gray matter volume was 663 mL in those with an active lifestyle, compared with 628 mL in those with an inactive lifestyle. That equates to a significant 5% difference (P value less than .05).
"That is a large number difference when you consider the tremendous biologic forces that have to be at work for gray matter volume to decrease," lead author Dr. Cyrus Raji said in a press briefing at the annual meeting of the Radiological Society of North America.
Prior research has looked at the influence of individual lifestyle factors such as obesity or walking on brain structure, but not a variety of activities, as was done in the current study. Improving lifestyle could reduce the risk for Alzheimer’s disease by 50%, resulting in 1.1 million fewer cases in the United States, said Dr. Raji, a radiology resident at the University of California, Los Angeles.
"In the United States, the lack of physical activity is the No. 1 most powerful lifestyle factor, contributing to 21% of cases of Alzheimer’s disease," he said. "Worldwide, it is the third most powerful risk factor after low educational attainment and smoking."
To determine how lifestyle influences brain structure, the investigators used MRI scans and clinical data collected over 20 years from 876 individuals enrolled at four sites in the Cardiovascular Health Study. The Minnesota Leisure Time Physical Activity Questionnaire was used to assess caloric expenditure during 15 different aerobic activities: swimming, hiking, aerobics, jogging, tennis, racquetball, walking, gardening, mowing, raking, golfing, bicycling, dancing, calisthenics, and riding an exercise bike. A technique called voxel-based morphology was used to quantify the amount of brain matter in the MRI scans.
The participants expended an average of 1,093 kcal/week. Overall, 42% were men, 88% were white, and about 25% had been diagnosed with Alzheimer’s disease or mild cognitive impairment (MCI). The cohort was largely overweight, with an average body mass index of 27 kg/m2. Their average age was 78 years.
The analysis controlled for head size; age; gender; body mass index, which has been related to brain structure and atrophy; small vessel ischemic disease, which reflects processes like diabetes and hypertension that can affect the brain; Alzheimer’s or mild cognitive impairment (MCI) status; and study site.
The most active participants burned an average of 3,434 kcal/week, compared with 348 kcal/week in the least active participants.
There was larger bilateral gray matter volume in the cingulate gyrus, hippocampus, and temporal lobes – areas responsible for memory and learning – among individuals who burned the most calories per week, compared with those who burned the fewest, Dr. Raji said.