CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 145 Relationships with others form a ubiquitous part of people’s every- day lives. In the classic analysis by Durkheim (1897/1951), suicide rates were higher among individu- als who were less socially integrat- ed than among those who had many social ties. The loneliness and despair that characterize a lack of social connections may be re- sponsible for such unfortunate out- comes. Less obvious, however, is the possibility that individuals with poor relationships may also be more at risk for physical ill- nesses, such as cardiovascular dis- ease, cancer, or infectious diseases. Is there evidence that such an asso- ciation exists? If so, how is it that social relationships influence such disease processes? The answer to the first question is relatively well documented. A re- view of large prospective studies comparing groups with differing degrees of social integration found that less socially integrated indi- viduals had higher mortality rates from all causes, including cardio- vascular mortality (House, Landis, & Umberson, 1988). In fact, the evi- dence linking social relationships to mortality was comparable to the evidence linking standard risk fac- tors such as smoking and physical activity to mortality. What is less known is the answer to the second question, that is, how social rela- tionships influence such long-term health outcomes. In this article, we review the evidence linking posi- tive aspects of social relationships (i.e., social support) to physiologi- cal processes. These associations are helping us to understand how relationships may influence physi- cal health outcomes such as cardio- vascular disease. Relationships serve important functions. For instance, most peo- ple can recall times when others made a difference in their lives by giving good advice (informational support); helping them feel better about themselves (emotional sup- port); directly providing aid, such as money (tangible support); or just “hanging out” with them (belong- ing support). The actual or per- ceived availability of these helpful behaviors by others is broadly de- fined as social support. Figure 1 depicts a simplified model of how social support might influence physical health outcomes (see Cohen, 1988, for a detailed model). The major pathway depict- ed in the top portion of the figure suggests that social support may be beneficial because it protects indi- viduals from the deleterious behav- ioral and physiological conse- quences of stress. In theory, social support may decrease how stressful an individual finds an event to be. For instance, a person who has sup- portive ties may experience less job stress because close others provide helpful information or reaffirm other aspects of that person’s life (e.g., familial role). The decreased stress appraisal may in turn influ- ence psychological processes such as negative mood states, feelings of personal control, and self-esteem. These psychological processes are thought to influence the cardiovas- cular, endocrine, and immune sys- tems, with implications for relevant disease outcomes (Kiecolt-Glaser & Glaser, 1995). For instance, over the long term, alterations in cardiovas- cular function (e.g., heart rate) may influence cardiovascular disorders such as high blood pressure, where- as a decrease in immune function may have implications for cancer and infectious diseases. However, even when individuals are not en- countering stressful life events, it is possible that social support may af- fect physiological processes by di- rectly influencing the psychological processes of self-esteem, feelings of personal control, and negative mood states. For instance, simply being in the company of close friends may elevate one’s mood. HOW MIGHT RELATIONSHIPS INFLUENCE PHYSICAL HEALTH OUTCOMES? Copyright © 1999 American Psychological Society Social Support, Physiological Processes, and Health Bert N. Uchino, 1 Darcy Uno, and Julianne Holt-Lunstad Department of Psychology and Health Psychology Program, University of Utah, Salt Lake City, Utah Abstract Social relationships serve important functions in peo- ple’s everyday lives. Epidem- iological research indicates that supportive relationships may also significantly protect individuals from various caus- es of mortality, including car- diovascular disease. An impor- tant issue is how social support influences such long-term health outcomes. In this article, we review evidence indicating that social support may influ- ence mortality via changes in the cardiovascular, endocrine, and immune systems. These data suggest that it may be worthwhile to incorporate so- cial-support interventions in the prevention and treatment of physical health problems. Keywords social support; cardiovascular function; immune function; health