title: Racial differences in the impact of social support on nocturnal blood pressure.
abstract: OBJECTIVE
  To investigate whether black and white adults benefit similarly from perceived social support in relation to blood pressure (BP) dipping during sleep.
  
  
  METHODS
  The Interpersonal Support Evaluation List (ISEL, 12-item version), which measures the perceived availability of several types of functional social support, was examined for interactive effects with race on dipping of mean arterial pressure (MAP), systolic blood pressure (SBP), and diastolic blood pressure (DBP) derived from 24-hour ambulatory blood pressure monitoring (ABPM). The sample consisted of 156 young to middle-aged adults (61 blacks, 95 whites; mean age = 35.7 years).
  
  
  RESULTS
  Mean ISEL scores did not differ between racial groups. Controlling for age, body mass index (BMI), resting BP, and socioeconomic status (SES), the interaction of social support by race yielded associations with nighttime dipping in MAP and DBP (p < .001) as well as SBP (p < .01). As ISEL scores increased among white participants, the extent of dipping increased in MAP, SBP, and DBP (p < .01), explaining 10%, 10%, and 8% of the variance, respectively. Conversely, black participants exhibited associations between increasing ISEL scores and decreasing levels of dipping in MAP, SBP, and DBP (p < .05), accounting for 9%, 8%, and 8% of the variance, respectively.
  
  
  CONCLUSIONS
  As perceived social support increased, white adults received cardiovascular benefits as suggested by enhanced nocturnal dipping of BP, but black adults accrued risks as evidenced by blunted declines in BP during sleep.
authors.affiliation: Department of Psychiatry, University of California San Diego, 9500 Gilman Dr., #0804, La Jolla, CA 92093-0804, USA. dccooper@ucsd.edu
authors.forename: Denise C
authors.initials: DC
authors.lastname: Cooper
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ziegler
authors.forename: Richard A
authors.initials: RA
authors.lastname: Nelesen
authors.forename: Joel E
authors.initials: JE
authors.lastname: Dimsdale