The study by Dr. David A. Bennett and his colleagues from the Rush Alzheimer's Disease Center is the first to examine the relations between social networks and Alzheimer’s disease pathology.

Researchers studied elderly people without known dementia who are participating in the Rush Memory and Aging Project, an epidemiological and clinicopathological study of aging and Alzheimer's disease that involves over 1,100 volunteers across northeastern Illinois. Brain autopsy was done at the time of death and post mortem data was available for analysis from the first 89 people.

"Many elderly people who have the tangles and plaques associated with Alzheimer's disease don't clinically experience cognitive impairment or dementia," said Bennett. "Our findings suggest that social networks are related to something that offers a 'protective reserve' capacity that spares them the clinical manifestations of Alzheimer's disease."

Participants in the study underwent clinical evaluations and 21 cognitive performance tests each year. To determine social network, participants were asked about the number of children they have and see monthly. They were asked about the number of relatives, excluding spouse and children, and friends to whom they feel close and with whom they felt at ease and could talk to about private matters and could call upon for help. They were asked to specify how many of these people they see monthly. Their social network was the number of these individuals seen at least once per month.

The relationship between the amount of Alzheimer’s disease pathology and cognitive performance changed with the size of the social network. As the size of the social network increased, the same amount of pathology had less effect on cognitive test scores.; Source: Rush University Medical Center