FRIDAY, Sept. 26 (HealthDay News) -- Cognitive and social activity in midlife may significantly reduce men's risk of dementia, says a U.S. study that followed 147 male twin pairs for 28 years.

Among the twins, higher cognitive activity scores predicted a 26 percent reduction in risk for developing dementia first. Twins who developed dementia first had significantly lower total cognitive activity scores than twins who didn't develop dementia.

The study found that reduced dementia risk was most strongly associated with participation in intermediate novel activities including home and family activities, visiting with friends and relatives, club activities (such as attending parties and playing card games), and home hobbies.

"These activities might be indicative of an enriched environment, which has been shown in animal models to enhance the creation of new brain cells and promote brain repair," noted study author Michelle C. Carlson, an associate professor in the department of mental health and the Center on Aging and Health at the Johns Hopkins Bloomberg School of Public Health, and colleagues.

Two other categories of cognitive activities -- novel and passive receptive -- also reduced dementia risk but not to the same degree as intermediate novel activities. Novel activities include reading, studying for courses, and extra work (overtime or other employment), while receptive activities include watching television, listening to radio, going to movies, or seeing theater, art and music shows.

The study was published in the September issue of Alzheimer's & Dementia.

"This fascinating study provides some of the first relatively strong evidence that cognitive activity, including social interaction, reduces dementia risk," William Thies, vice president of medical and scientific relations at the Alzheimer's Association, said in an association news release. "The results extend earlier twin study data that showed the beneficial impact of similar activities on Alzheimer's and dementia risk in women."

A growing body of evidence suggests a link between low social activity and increased risk for Alzheimer's disease, and that mid- and late-life social activity is associated with better mental and physical health.

"Overall, these findings suggest that engaging in activities that incorporate both cognitive and social activity might confer protection against Alzheimer's and dementia, particularly among those at elevated genetic risk for the disease," Carlson said. "These results can help inform future preventive interventions, especially because they point to a range of activities that individuals are likely to maintain, because they are rewarding, entertaining and engaging."

Carlson and her colleagues wrote that their findings "have immediate implications for a generation of male baby boomers approaching retirement. Approximately one third of many individuals' lives will be spent after retirement. The expansion of the human life span makes it imperative to identify lifestyle opportunities that increase health and 'add life to years.'"

More information

The U.S. National Institutes of Health has more about Alzheimer's Disease prevention.