tered in one cause of death. Those who had few social ties were at increased risk of dying from ischemic heart disease; cerebrovascular and circulatory disease; cancer; and a final category that included respiratory, gastrointestinal, and all other causes of death. Several other studies, both in the United States and across the world, have replicated the basic observation that social isolation increases the relative risk of mortality (Berkman, 1995; Berkman and Kawachi, 2000; Blazer, 1982; Cohen, 1988; House et al., 1982, 1988; Kaplan et al., 1988; Orth-Gomer and Johnson, 1987; Pennix et al., 1997; Schoenbach et al., 1986; Seeman et al., 1988, 1993, 1996; Sugisawa et al., 1994; Welin et al., 1985).

Powerful epidemiologic evidence consistently supports the notion that social ties, especially intimate ties and emotional support provided by them, promote increased survival and better prognosis among people with serious cardiovascular disease (Berkman et al., 1992; Case et al., 1992; Krumholz et al., 1998; Orth-Gomer et al., 1988; Oxman et al., 1995; Ruberman et al., 1984; Williams et al., 1992). Most studies find that social networks are related more strongly to mortality than to the incidence of myocardial infarction (MI) (Kawachi et al., 1996; Reed et al., 1983; Vogt et al., 1992; but see Orth-Gomer et al., 1993). A similar pattern of associations between social integration and incidence versus recovery from stroke has been observed (Colantonio et al., 1992, 1993; Friedland and McColl, 1987; Glass and Maddox, 1992; McLeroy et al., 1984; Morris et al., 1993). For example, although social integration was not associated with the incidence of stroke in an elderly cohort (Colantonio et al., 1992), poststroke recovery after 6 months was significantly related to prestroke social integration (Colantonio et al., 1993). Socially isolated people exhibited worse functional status 6 months after a stroke (Glass et al., 1993), as measured by impairments in activities of daily living and frequency of nursing home placement.

Adverse Interactions

Being part of a social network, however, can have harmful as well as positive consequences, because the value to the individual of such ties depends upon the character of that network as well as on the strength of those ties. Membership in networks, for example, provides access to domestic, economic, and informational resources (Uehara, 1990). If a person is tied to a tightly knit group, the resources available through that group, especially informational resources, could be limited. Sometimes

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