Hostility moderates the effects of social support and intimacy on blood pressure in daily social interactions.

OBJECTIVE This study sought to determine the role of hostility in moderating the effects of positive social interactions on ambulatory blood pressure (ABP). DESIGN Participants (341 adults) completed the Cook-Medley Hostility Scale and underwent ABP monitoring, assessed every 45 min during waking hours across 6 days. An electronic diary measuring mood and social interactions was completed at each ABP assessment. MAIN OUTCOME MEASURES The dependent variables from the ABP monitor included systolic blood pressure, diastolic blood pressure, and heart rate. RESULTS Different patterns of ambulatory diastolic blood pressure (ADBP) responding to social interactions perceived as intimate or supportive among high- versus low-hostile individuals were observed. Higher intimacy ratings were linked to reductions in ADBP among low-hostile but not high-hostile individuals. Conversely, high-hostile, but not low-hostile, individuals showed increases in ADBP to situations rated high in social support. Although findings for ambulatory systolic blood pressure were nonsignificant, the pattern of results was similar to ADBP. CONCLUSION Hostile individuals may find offers of support stressful and may fail to benefit from intimacy during daily life. The pathogenic effects of hostility may be mediated in part by responses to social interactions, both positive and negative.