Baltimore ? The variety and not the intensity of exercise may help ward off dementia, suggests a new study that found a lower risk of that condition among older people with many pastimes, ranging from gardening to aerobics.

“It’s not necessarily the energy you spend,” said Dr. Constantine Lyketsos, a Johns Hopkins University epidemiologist and the study’s lead author. “It’s the variety that matters.”

The findings come as no surprise to 73-year-old Blanche Shoul, who walks daily at the Towson Town Center, where she also works as a customer service representative.

“I’ve been doing it all my life,” she said. “Mentally, I think I’m just as sharp as when I worked for the state for 31 years.”

Shoul says she also bicycles and exercises with weights twice a week, as well as doing aerobics and playing board games.

Researchers tracked 3,375 men and women over age 65 from 1992 to 2000, surveying them on the kinds of activities they did. Those doing the widest variety were far less likely to develop dementia, the researchers found.

The volunteers were questioned about the frequency and duration of the 15 most common physical activities in older adults — walking, household chores, mowing, raking, gardening, hiking, jogging, biking, exercise cycling, dancing, aerobics, bowling, golfing, general exercise and swimming.

The findings also suggest that even sedentary activities such as card-playing may be beneficial, Lyketsos said.

“Exercising your body is exercising your brain, by the way, because the brain is central to the coordination of any exercise movement,” he said.

The reason for the link between the number of activities and the lower rate of dementia is not clear, Lyketsos said, but it may be that a variety of activities keeps more parts of the brain active. Or it could be that the variety may show the person is more socially and physically active overall.

Dementia encompasses a group of diseases, including Alzheimer’s disease, that gradually destroy brain cells and lower mental function, according to the Alzheimer’s Assn.