A Prospective Study of Social Isolation, Loneliness, and Mortality in Finland

OBJECTIVES: To estimate the simultaneous effects of social isolation and loneliness on mortality. METHODS: We analyzed a representative Finnish sample (n = 8650) from the cross-sectional Living Conditions Survey of 1994, with a 17-year follow-up period (1995-2011), by using Cox regression models adjusted for several possible confounding variables. We examined the possible nonlinear threshold effect of social isolation on mortality. RESULTS: The analyses revealed that social isolation predicted mortality even after we controlled for loneliness and control variables. The connection between social isolation and mortality was linear in nature and there was no synergistic effect between social isolation and loneliness. The effect of loneliness became nonsignificant when studied simultaneously with social isolation. CONCLUSIONS: This study reveals strong evidence for an adverse effect of social isolation on mortality. Social isolation and loneliness seem to have distinct pathways to mortality and health. The results imply that the risk of mortality exists along a continuum, affecting not only those who experience extreme social isolation, but also those who suffer from mild to progressively increasing intensity of isolation.