social ties and mortality was … independent of the self-reported physical health status at the time of the 1965 survey, year of death, socioeconomic status, and health practices such as smoking, alcoholic beverage consumption, obesity, physical activity, and utilization of prevention health services as well as a cumulative index of health practices" (p. 186). Social support in this study was defined as the presence of a spouse, contact with friends, or church and community group membership.

Seventeen-year mortality data from the Alameda County Study were used to examine the relative importance of social ties as predictors of survival at different ages.43 Comparisons of the relative importance of four types of social ties reveal an interesting shift across the age groups. Marital status assumes primary importance for those aged less than 60 years at baseline. However, ties with close friends or relatives assume greater importance for those aged 60 and older.

A study reported by Blazer4 of 331 persons aged 65 and older has a similar finding of a higher death rate among persons who were socially deprived. This effect on mortality occurred over a shorter period—30 months. The measurement of social isolation was based on three factors: roles and available attachments, perceived social support, and frequency of social interactions.

A similar finding of decreased mortality risk associated with higher levels of social relationships was reported by House and coworkers,22 but the finding in this instance was limited to men. The study, the Tecumseh County Health Survey, followed a cohort of 2,754 adults for 9 to 12 years. Trends were similar for women but generally nonsignificant. The measure of social support comprised intimate social relationships, formal organizational involvement outside of work, active and relatively social leisure, and passive and relatively solitary leisure. The findings of these large studies appear to have relevance for each stage of prevention.

There have been other major studies that looked at the relationship of social networks to specific diseases. Haynes,19 for example, examined coronary heart disease using cross-sectional data from the Framingham study. He showed that, for men and women over the age of 65, marital dissatisfaction or disagreements were significantly related to the prevalence of coronary heart disease. This association occurred only for the older age group (aged 65 and older), suggesting that risk factors may change at different ages.27

Reed and colleagues36 reported that prevalence rates for myocardial infarction, angina, and all coronary heart disease were associated with a lack of social network (the study controlled for 12 other

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