The amount of trust, reciprocity and cooperation among community members working together to achieve common goals—referred to as “social capital” by behavioral scientists—is a predictor for sexually transmitted infectious diseases and risky sexual behaviors, according to an Emory study.

The investigators found that lower amounts of social capital were associated with higher rates of AIDS and other sexually transmitted diseases, as well as with higher rates of risky adolescent sexual behaviors. The research was reported last month at the 14th Inter-national AIDS Conference in Barcelona, Spain.

“Although the amount of social capital in a particular society previously has been
correlated with violence and mortality, its relationship to infectious diseases has received little attention,” said David Holtgrave, professor of behavioral science and health education in the Rollins School of Public Health and one of the study investigators. “In making that connection for the first time, we found that social capital is a very good predictor of infectious diseases including AIDS and sexually transmitted diseases, as well as a predictor of adolescent risk for these diseases.”

In 1999, the investigators examined the relationship between social capital, poverty and income inequality, AIDS case rates and STD rates (syphilis, gonorrhea and chlamydia) in the 48 contiguous U.S. states. They found that social capital was a significant predictor of all four diseases, explaining 25–45 percent of the variance in the rate of each disease.

They also found that social capital was a significant predictor of 10 out of 14 behavioral variables, including current sexual activities, early sexual debut and greater number of partners. Poverty and income inequality were much less strong predictors of these disease and behavior outcomes.

In order to measure social capital, the investigators used Putnam’s measure of state-level social capital. The measure is a composite of 14 different variables, some of which include the number of social organizations in a state; the reported level of participation in those social activities with friends; the extent to which individuals report trusting each other; and overall voting rates.

The investigators measured disease rates using Centers for Disease Control and Prevention (CDC) surveillance system measures of state-level AIDS cases, gonorrhea, syphilis and chlamydia. Behavioral outcome measures were obtained through the CDC’s Youth Risk Behavior Survey, which includes seven aspects of adolescent HIV-related sexual risk behavior.

“Our findings tell us that the amount of trust and cooperation in a society—social capital—should be considered in the development of HIV and STD prevention interventions,” Holtgrave said. “We also have to extend our study of social capital beyond sexually transmitted diseases to all the nationally notifiable infectious diseases, including, among others, tuberculosis and hepatitis.”