Overall, the mean and standard deviation values of the study variables portray a generally healthy and normative sample (). Average levels of CRP were low: 46 adolescents had CRP levels in the low-risk range (CRP = <1), 13 adolescents fell into the intermediate-risk category (CRP = 1-3), and only 7 adolescents were in the high-risk category (CRP = >3). There were no significant differences in levels of CRP according to adolescents’ gender and ethnic background, t values(67) = 0.65-1.48, p values = .15-.52. BMI was within normal range and participants reported low levels of substance use.
Interpersonal stress was not uncommon, occurring on approximately one third of days, but it also was not extremely frequent. In terms of the occurrence of specific events across the 2-week period, the most common event was argued with friend (60.9% of adolescents reported it occurring at least once), followed by argued with mom (58%), argued with dad (37.7%), being punished or disciplined at home (34.8%), argued with another family member (33.3%), something bad happened to someone else in the family (26.1%), parents had argument (20.3%), punished at school (18.8%), harassed at school (8.7%), and harassed outside of school (7.2%). The rates of family conflict and peer harassment are similar to those obtained in other studies of adolescents (1
), but there have been no previous studies that estimated the daily frequency of the other events. In terms of the average number of events reported per day, 13% of the sample reported no events occurring each day. An additional 72.5% reported an average of >0 but <1 event per day, 13.1% reported 1 to 2 events per day, and 1.4% reported an average of >2 events per day.
Adolescents also reported few stressful life events and fairly low levels of daily emotional distress and rejection sensitivity.
Bivariate correlations among the study variables are presented in and show significant associations of interpersonal stress with CRP, life events, rejection sensitivity, and distress. In addition, individuals with a higher BMI also had higher levels of CRP.
Results of the hierarchical regression are presented in . As shown in Model 1, adolescents who reported more frequent interpersonal stress had significantly higher levels of CRP. This association existed even after controlling for the adolescents’ SES, BMI, and substance use (Model 2). In addition, the link between interpersonal stress and CRP was significant above and beyond life events, rejection sensitivity, and psychological distress (Models 3 and 4).
Hierarchical Regression Predicting CRP From Interpersonal Stress, SES, BMI, Substance Use, Major Life Events, Rejection Sensitivity, and Distress
Because the blood samples were obtained at variable periods after the adolescents completed the reports of daily interpersonal stress, an additional analysis was conducted to determine whether the strength of the association between stress and CRP varied according to the number of months between the two measurements. The interaction between daily interpersonal stress and the length of the interval between the measurements in predicting CRP, however, was not significant (β = 0.08, B = 0.02, SE = 0.11, p = .89).
Finally, using the 55 out of 69 participants for whom an identical measure of daily interpersonal stress was available at the 10th grade, a regression was conducted in which 10th grade level of daily interpersonal stress was controlled at the same time as using 12th grade daily interpersonal stress to predict CRP. This allowed us to control for stable, individual differences and to examine the impact of change in daily interpersonal stress on CRP. Results indicated that the 12th grade measure was a significant predictor of CRP (β = .34, B = 2.52, SE = 1.20, p < .05), whereas the 10th grademeasure was not (β = -0.01, B = -0.06, SE = 1.25, p = .95). These results were obtained despite the fact that the 10th grade and 12th grade measures of interpersonal stress were highly correlated with one another (r = .59, p < .001).