This study tested two hypotheses of associations between dimensions of social connectedness and cardiovascular
reactivity to acute stress: (1) high social support predicts diminished cardiovascular responses to stress (i.e., the
stress-buffering model of social support), and (2) diminished cardiovascular responses predict lower social
participation, a form of motivated behaviour. Participants (N = 606) in the main Midlife in the United States
study completed measures of social support and social participation and underwent psychophysiological stress
testing. In unadjusted analyses, social support was positively, rather than inversely, associated with reactivity.
Results withstood adjustment for several control variables, but not for depressive symptoms, which was asso ciated with diminished reactivity. Further, diminished reactivity was associated with lower social participation,
but not in fully adjusted models. No robust evidence was observed for either the stress-buffering model, or for an
association between diminished reactivity and lower social participation. The implications for our understanding
of links between social connectedness and cardiovascular reactivity are discussed.