واکنش پذیری استرس و آسیب پذیری به خلق و خوی افسرده در دانشجویان

Abstract Two studies reported here found that in response to common, minor stressors, stress reactivity (defined as mean stress per stressor) was a stronger predictor than total stress of depressed mood in traditional and nontraditional college men and women. A prospective study found individual reactivity scores varied over time, but relationships between stress and depressed mood held across four monthly assessments. Stress reactivity also accounted for more incremental variance in depressed mood than total stress after controlling for previous depressed mood. When students in the cross-sectional study were classified into reactivity groups, scores for depressed mood increased steadily for students in the very low through high reactivity groups, as did percentages of students with depressed mood scores that might indicate depression in normal populations. This study also found that stress reactivity was more strongly correlated than total stress with neuroticism and its facets (or traits) of depression, anxiety, and vulnerability to stress in the five-factor model of personality. Taken together, these studies suggest that elevated stress reactivity to minor stressors may indicate diminished ability to cope with everyday challenges and may predict increased vulnerability to depressed mood in a normal population.

. Introduction The assumption that stress accumulates over time to cause or trigger episodes of disorder (Rabkin & Struening, 1976) has guided research in stress and health for over three decades. It was a guiding principle in the pioneering development of the Social Readjustment Rating Scale (Holmes & Rahe, 1967) and subsequent life events inventories, which measure cumulative stress from exposure to minor and major events requiring adaptive responses. Sufficient stress to trigger disorder may accumulate from exposure to one or more very stressful events or a greater number of less stressful events. Many studies have supported this model by demonstrating reliable, but generally modest correlations between cumulative life events stress and negative physical and psychological health outcomes (Johnson & Sarason, 1979). More recent efforts to assess stress have often employed “hassles” inventories, which measure stress from commonly occurring, minor stressors. There are theoretical and practical reasons for this approach. Many researchers found that major stressors occurred too infrequently to account for most of the stress that people experienced. Furthermore, many researchers study stress and outcomes in convenience samples such as college students, who generally experience few major stressors and little serious disorder, but frequent minor stressors, negative mood states, and deficits in performance. Hassles inventories are also based on the assumption that stress accumulates to cause or trigger negative outcomes. This approach has been successful and many studies found cumulative stress from minor stressors was a stronger predictor of physical and psychological disorder than stress from major life events, even when the same studies employed both measures of stress (DeLongis et al., 1982, Kanner et al., 1981 and Monroe, 1983). Hassles and life events inventories differ primarily in the nature of events listed. Life events inventories include items that cover a broader range of potential stress and required adaptation. Although the cognitive-transactional model of stress (Lazarus & Folkman, 1984) posits that individuals may vary greatly in appraising the stressfulness of any event, life events inventories include some items that most people might rate as slightly stressful and some items that most people might rate as extremely stressful. Individuals could achieve high cumulative stress scores by experiencing one or more very stressful events or a greater number of less stressful events. In contrast, and consistent with their name, hassles inventories do not contain any items that most people would consider especially stressful. They were developed in response to the hypothesis that the cumulative effect of frequent exposure to everyday stressors could trigger disorder. Yet, some hassles inventories allow respondents to rate minor stressors as extremely stressful and some respondents do so. Brantley and Jones (1989) suggested that individuals who rate minor stressors as very stressful may be dispositionally or temporarily more vulnerable to stressors and less able to cope. They might be expected to accumulate stress more quickly and be more likely to experience negative affective states than individuals who rate minor stressors as less stressful. It is also possible, however, that such individuals by virtue of their vulnerabilities to stress, may experience greater negative affect even if they do not accumulate more total stress. Felsten (2002) tested this hypothesis by measuring mean stress per stressor (stress reactivity) and total stress in response to minor stressors, and found stress reactivity was the stronger predictor of depressed mood in college women. Reactivity was also moderately correlated with neuroticism, a stable dimension of personality associated with ineffective coping, vulnerability to stress, poor adjustment, and negative affect (Costa & McCrae, 1992). Based on this association, the author suggested that greater stress reactivity in response to minor stressors might be a stable marker for vulnerability to stress and a predictor of negative outcomes. The study was limited in that it included only women, did not evaluate associations between stress reactivity and personality in detail, and provided no actual test of the stability of stress reactivity. The present report addressed those limitations by reevaluating archival data, some of which have been previously published (Felsten, 1996a and Felsten, 1996b). These archival data contain measures appropriate for addressing the issues described above, but were not previously used in that manner. 1.1. Study 1 Study 1 was a reanalysis of some of the published data from a cross-sectional study (Felsten, 1996a) used to evaluate expressive and neurotic hostility in the context of the five-factor model of personality (Costa and McCrae, 1992 and McCrae and John, 1992). The reanalysis permitted evaluation of how strongly total stress and stress reactivity predicted depressed mood in men and women and also allowed a more detailed evaluation of personality correlates of stress reactivity. Data from the hostility inventory were not used in the reanalysis.

Results Mean scores for the monthly measures of stress and depressed mood in men and women appear in Table 4. Independent samples t-tests found no gender difference for any measure and data were combined for further analyses. Repeated measures analysis of variance (using the Greenhouse-Geisser epsilon to correct for violations of sphericity) found overall differences across assessments in number of stressors F(3, 117)=30.1, P<0.001, total stress F(3, 117)=17.0, P<0.001), and depressed mood F(3, 117)=2.8, P=0.05. Contrasts showed number of stressors and total stress decreased from month 1 to month 2 to month 3, and then leveled off, whereas depressed mood was higher in the first month than in the next 3 months. Stress reactivity did not differ across assessments. These analyses assessed systematic changes over time in mean measures, but did not evaluate individual variability irrespective of the order of assessments. To test whether individuals varied in reactivity over time, four variables were created for each individual's lowest to highest reactivity scores. Repeated measures analysis of variance (Greenhouse–Geisser corrected) found an overall significant difference, F(3, 117)=61.1, P<0.001, and contrasts found each level of reactivity differed from every other level, all Fs(1, 39) > 38.6, all Ps<0.001. Thus, individual's reactivity varied over time, but not in a systematic manner. Table 4. Descriptive statistics for measures of stress and depressed mood Men (n=17) Women (n=21) M S.D. M S.D. Month 1 Number of stressors 30.4 12.7 32.2 12.9 Total stress 49.3 33.0 61.6 40.5 Stress reactivity 1.7 1.0 1.9 1.0 Depressed mood 8.1 7.7 10.6 9.0 Month 2 Number of stressors 23.4 13.9 25.2 10.7 Total Stress 37.1 29.5 49.0 28.5 Stress reactivity 1.7 1.0 1.9 1.0 Depressed mood 6.1 7.0 9.4 9.3 Month 3 Number of stressors 20.5 15.2 20.1 8.1 Total stress 30.7 27.0 38.3 25.4 Stress reactivity 1.5 1.1 1.9 1.0 Depressed mood 6.3 8.0 8.0 6.4 Month 4 Number of stressors 19.9 14.7 20.5 10.0 Total stress 28.4 22.7 38.1 29.6 Stress reactivity 1.6 1.1 1.8 1.0 Depressed mood 6.2 8.4 9.1 10.0 Table options Relationships were evaluated between stress measures and depressed mood for the four monthly assessments using correlations and linear regression analysis. Correlations appear in Table 5. Almost all correlations between either measure of stress and depressed mood were strong, but at each assessment, the correlation was stronger for stress reactivity than for total stress. Partial correlations with depressed mood were stronger for stress reactivity controlling for total stress than for total stress controlling for stress reactivity. Linear regression analysis found that Time 3 stress reactivity accounted for an additional 17.8% of the variance in Time 3 depressed mood, controlling for Time 2 depressed mood, F(1, 37)=20.1, P<0.001. The full model accounted for 67.4% of the variance, F(1, 37)=38.2, P<0.001. Time 4 stress reactivity accounted for 8.2% of incremental variance in Time 4 depressed mood after controlling for Time 3 depressed mood, F(1, 37)=10.7, P<0.01. The full model accounted for 71.7% of the variance, F(1, 37)=46.9, P<0.001.When total stress was substituted in these analyses, it accounted for less than half the incremental variance accounted for by stress reactivity. Neither Time 2 stress reactivity nor total stress added to the variance in Time 2 depressed mood contributed by Time 1 depressed mood. Table 5. Correlations and partial correlations between depressed mood and measures of stress Depressed mood Bivariate Partiala Month 1 Total stress 0.697*** 0.337* Stress reactivity 0.786*** 0.586*** Month 2 Total stress 0.571*** 0.232 Stress teactivity 0.709*** 0.550*** Month 3 Total stress 0.603*** 0.238 Stress reactivity 0.728*** 0.552*** Month 4 Total stress 0.603*** 0.359* Stress reactivity 0.720*** 0.584*** a Controlled for other measure of stress. ∗ P<0.05. ∗∗∗ P<0.001.