Several years ago, however, the research team began analyzing blood samples drawn from 388 men and 438 women when they entered the MacArthur study. Levels of the participants' biomarkers were correlated with their degree of social relationships.

Researchers failed to find any correlation between the degree of social isolation in women and their levels of the inflammatory biomarkers.

"Men may respond differently than women to social relationships," Loucks said.

"Women also live longer than men," he added. "So another possibility is that in this particular age group, 70 to 79, men's inflammatory biomarkers may be more influenced by social relationships than women's at that age."

Among the 388 men, CRP levels were 3.69 for those in the lowest fourth of social network index (i.e. those most socially isolated) compared to 2.33 for those in the highest fourth. Levels of IL-6 were 5.54 for those in the lowest fourth and 4.10 in the highest fourth. Fibrinogen levels were only slightly different: 2.98 compared to 2.73.

When the researchers statistically controlled for age, education, race, physical functioning, and the presence of other diseases, they still found a significant inverse correlation between people's social network and their levels of the three biomarkers.

However, when the team further controlled for behavioral factors that can affect health such as smoking, alcohol consumption, physical exercise and obesity the association was no longer statistically significant.

This last finding shines further light on how social relationships may influence a person's level of biomarkers because social relations may influence behavior, Loucks noted.

"If your spouse eats a high-fat diet, chances are you will eat a high-fat diet, or if your spouse exercises, chances are you will too," he said. "People who have a low variety of social
'"/>

Contact: Carole Bullock
carole.bullock@heart.org
214-706-1279
American Heart Association
11-Nov-2003