'Core' and 'extended' social networks in relation to health and illness.

This paper considers several models of the nature of the association that has been found between characteristics of social networks and health. Such an association does not appear to be adequately accounted for by a deleterious effect of illness on social contact, nor by the role of social networks in mediating health-related practices or in buffering the effects of stress. Thus the proposition is tentatively warranted that the social network is more directly and causally involved in health outcomes--perhaps through the impact of social feedback as mediated by the network. It is argued that the social processes that affect the association between networks and health involve a larger social unit than the small core networks that have generally been the focus of study. Assuming that the individual's susceptibility to illness is affected by the adequacy of the core network, we must deal with the fact that the vulnerability of the core network to loss without adequate replacement is, in turn, affected by the structure of the larger, extended network in which the core network is embedded. By shifting attention to these extended networks, it should also become possible to integrate findings from network studies with more traditional epidemiological findings relating such macro-variables as social class to illness.