proximal social interactions. Survival of newborns depends on nurturance by others, and extensive lines of inquiry illustrate the centrality of social ties across the life course. A large body of epidemiological findings document the links between social relationships and mental and physical health outcomes, including mortality. Disruption of personal ties, loneliness, and conflictual interactions are key sources of stress, while supportive social connections and intimate relations are vital sources of emotional strength.
What is not well understood, however, are the connections between these realms of personal connection and gene expression, brain structure and function, neuroimmunological activity, and ultimate disease and health outcomes. Reflecting the focus on pathways, there is a pressing need to assess cumulative long-term relational profiles, particularly their emotional features, and link them to cumulative physiological profiles, such as allostatic load. In the extant literature, analyses also tend to focus on average responses and frequently relegate individual differences to error variance. Given the need to understand multiple pathways to diverse health outcomes, such individual differences should be treated as a crucible for theory construction and empirical testing.
NIH studies of the links between the social world and health should focus on the underlying and causal (including reciprocal) mechanisms in both animals and humans. The objective is to understand interrelationships between social interaction and correlative biological phenomena. This work should include:
studies that explicate the links between social relationships and gene expression, brain structure and function, and neuroimmunological activity;
investigations that assess how social ties influence health practices and behaviors;
longitudinal studies that link cumulative social relational profiles with cumulative biological profiles;
increased emphasis on the collection of biomarkers in epidemiological studies of social relationships and health;
extensions of traditional laboratory studies to include experience sampling methodologies and corresponding ambulatory neurobiological assessments;
multilevel integrative studies working at the interface of social interaction, emotion, and brain activity and downstream endocrinological and immunological processes.
The preceding emphasis on social environments reflects primarily individual-level influences and processes. This report underscores the impor-