Background Having a larger social network has been shown to have beneficial effects on health and survival in adults, but few studies have evaluated the role of network diversity, in addition to network size. We explore whether social network diversity is associated with mortality, cognition and physical function among older black and white adults.

Methods Data are obtained from the Chicago Health and Aging Project, a longitudinal, population-based study of adults aged 65 years and older at baseline. Using Cox proportional hazards regression, we estimate the hazard of mortality by network diversity (n=6497). The association between network diversity and cognition (n=6560) and physical function (n=6561) is determined using generalised estimating equations. Models were adjusted for age, gender, race, socioeconomic status, marital status and health-related variables.

Results In fully adjusted models, elderly with more diverse social networks had a lower risk of mortality (HR=0.93, p<0.01) compared with elderly with less diverse networks. Increased diversity in social networks was also associated with higher global cognitive function (coefficient=0.11, p<0.001) and higher physical function (coefficient=0.53, p<0.001).

Conclusions Social networks are particularly important for older adults as they face the greatest threats to health and depend on network relationships, more than younger individuals, to meet their needs. Increasing diversity, and not just increasing size, of social networks may be essential for improving health and survival among older adults.