Staying Social May Keep Dementia at Bay

It's impossible to say how many friends and family makes up a big enough social circle to be protective, the researcher said. "Two or fewer is probably not a sufficient amount. You could have three really close friends [or family] and be fine," Crooks speculated.

"We can't tell you what the magic number is," she said.

And she emphasized that her team found only an association between social networks and reduced risk of dementia, which doesn't point to a cause-and-effect relationship, necessarily.

"There could be a person with one person [in his or her social network] who is doing perfectly fine," she said.

While more study is needed to zero in on exactly which aspects of social support are linked with a decrease in dementia risk, Crooks said the findings make perfect sense, neurologically speaking. "The more interaction, the more you challenge your brain."

Dr. William Thies, vice president of medical and scientific relations at the Alzheimer's Association, said the finding "fits with a large body of evidence that being isolated is bad for you."

But he added, the finding is merely an association, not cause and effect.

"You don't know whether the bigger network prevents Alzheimer's or [whether] people who don't get Alzheimer's maintain bigger networks," he said.

More information

To learn more about dementia, visit the National Institute on Aging.

Keeping Your Mind HealthyIf you hope to maintain cognitive function as long as possible, there are a number of lifestyle measures that may be protective, according to the Alzheimer's Association:Stay socially and mentally connected.Keep tabs on your cholesterol level and blood pressure readings to keep them in the normal ranges. High levels of cholesterol and high blood pressure boost the risk of dementia. Manage your body weight. Obesity in middle age doubles the risk ofdementia later. Adopt a brain-healthy diet. Eat more vegetables and less fat. Pickdark-skinned fruits and vegetables, which have the highest levels of natural antioxidants -- for instance, kale, spinach, Brussels sprouts, broccoli, beets, red bell peppers, prunes, raisins, blueberries, blackberries and plums.

SOURCES: Valerie C. Crooks, D.S.W., researcher, Kaiser Permanente Southern California, Pasadena, Calif.; William Thies, Ph.D., vice president, medical and scientific relations, Alzheimer's Association, Chicago; July 2008,American Journal of Public Health