Perceived Stress, Life Events, Dysfunctional Attitudes, and Depression in Adolescent Psychiatric Inpatients

Transcription

1 Journal of Psychopathology and Behavioral Assessment, Vol. 17, No. 1, 1995 Perceived Stress, Life Events, Dysfunctional Attitudes, and Depression in Adolescent Psychiatric Inpatients Rod A. Martin, 1 Shahe S. Kazarian, 2 and Hans J. Breiter 2 Accepted for publication: November 29, 1994 Hewitt, Flea, and Mosher (1992) examined the factor structure of the Perceived Stress Scale (PSS) and its relation to depression in adult psychiatric patients. This study sought to replicate and extend their findings, using a sample of 203 adolescent psychiatric inpatients. All patients admitted to the adolescent unit in a psychiatric hospital over a 3-year period were administered the PSS, as well as measures of depression, life events, dysfunctional attitudes, and intellectual abilities. Consistent with Hewitt et al., two factors were found in the PSS, reflecting perceived distress and perceived coping ability. Regression analyses indicated that, for males, both factors account for independent variance in depression, whereas for females, only the distress factor is related to depression. In addition, for both male and female, dysfunctional attitudes account for significant variance in depression in addition to PSS, but negative life events do not. None of the variables were related to intellectual abilities. Implications for clinical assessment and intervention are discussed. KEY WORDS: Perceived Stress Scale; Children's Depression Inventory; negative life events; dysfunctional attitudes; adolescent psychiatric inpatients. INTRODUCTION A considerable amount of research has investigated the relationship between life stress and psychological disturbance among nonclinical adolescents (cf. Johnson, 1986; Compas, 1987). However, very little research 1Department of Psychology, University of Western Ontario, London, Ontario, Canada. 2Department of Psychology, London Psychiatric Hospital, London, Ontario, Canada /03004) Plenum Publishing Corporation

2 82 Martin, Kazarian, and Breiter of this sort has been conducted among adolescent psychiatric inpatients. Research examining the relationship between major life events and depression in nonclinical adolescents has produced mixed results. Some studies have reported concurrent correlations ranging from.22 to.38 (e.g., Compas, Slavin, Wagner, & Vannatta, 1986; Swearington & Cohen, 1985). Other research using a prospective design has found little relationship between life events and subsequent depression after controlling for prior levels of disturbance (e.g., L. H. Cohen, Burt, & Bjork, 1987; Compas, Howell, Phares, Williams, & Giunta, 1989). In a 5-year longitudinal study of childhood depression, Nolen-Hoeksema, Girgus, and Seligman (1992) found that negative life events predicted depressive symptoms in early childhood, but no longer predicted significant variance in depression in later childhood or early adolescence (7th grade). Compas (1987) has suggested that chronic strains and minor daily stressors (hassles) may be more important than major life events in predicting psychological and behavioral difficulties during adolescence. In support of this hypothesis, Wagner, Compas, and Howell (1988) found evidence that negative daily events mediate the relationship between major stressors and psychological symptomatology among older adolescents. Similar findings were obtained by Compas, Howell, Phares, Williams, and Ledoux (1989) in a study of younger adolescents and their parents. In reviewing the literature on stress and psychiatric symptoms in adults, Hewitt, Flett, and Mosher (1992) suggested that both life events and daily hassles measures may be limited in their applicability tocertain populations because they may not adequately sample relevant events and other important sources of stress. These authors suggested that the Perceived Stress Scale (PSS; S. Cohen, Kamarck, & Mermelstein, 1983) is a viable alternative to these measures, as it assesses the degree to which individuals appraise their life situations as stressful, rather than measuring the frequency or presence of specific stressful events. As such, the PSS is also consistent with current conceptualizations of stress that emphasize the importance of subjective appraisals of stress and coping ability rather than the objective occurrence of events (cf. Lazarus & Folkman, 1984). S. Cohen (1986) also argued in favor of the PSS as a useful stress measure, as "it does not tie appraisal to particular situations, it is sensitive to the nonoccurrence of events as well as to ongoing life circumstances, to stress resulting from events occurring in the lives of friends and relatives, and to expectations concerning future events" (p. 718). In response to criticisms that the PSS is confounded with measures of psychopathology (Lazarus, DeLongis, Folkman, & Gruen, 1985), S. Cohen (1986) cited data indicating that the PSS predicts subsequent psychological and physical symptoms even after controlling for prior symptom levels. Martin (1989)

3 Perceived Stress and Depression 83 has suggested that the PSS may best be conceptualized as measuring the outcomes of person-environment stress transactions. In other words, whereas major life stress and daily hassles measures attempt to assess the objective occurrence of environmental events independent of subjective appraisals and coping, the PSS measures the cognitive and affective outcomes of all factors that contribute to the experience of stress, including objective environmental events, subjective appraisals, coping, and personality and other resources. As such, it may be viewed as a final mediating link between various types of stress and their adaptational outcomes such as physical and psychological problems. Hewitt et al. (1992) examined the factor structure of the PSS and its relationship with self-reported depression in a sample of 98 adult psychiatric patients. They found that total PSS scores were quite strongly correlated (r =.57) with the Beck Depression Inventory (BDI). In addition, the mean score for PSS was higher in this clinical sample than that found previously with nonclinical populations, and women in their sample had significantly higher mean PSS scores than men. Their factor analysis revealed two main factors in the PSS, which they labeled Perceived Distress and Perceived Coping. Women scored higher than men on the Perceived Distress factor, but there was no sex difference on the Perceived Coping factor. Among women, both Distress and Coping correlated independently with the BDI, whereas for men, only the Distress factor correlated with this depression measure. The authors concluded that the two factors should be considered separately in future research, and that they assess two aspects of stress-related appraisals that have both theoretical and clinical relevance. The present study was designed to replicate and extend the Hewitt et al. (1992) findings with a larger sample of adolescent psychiatric inpatients, in order to determine whether the same factor structure for the PSS occurs with adolescent patients as with adults. In this study, we used the Children's Depression Inventory (CDI; Kovacs, 1981), which was derived from the BDI, as our measure of depression. In addition, we extended the analyses by including several other measures. First, we included the Life Events Scale for Adolescents (LES-A; Coddington, 1984), a measure of major life events, in order to compare more directly the degree to which the PSS and major life events are related to depression in this population. Second, we administered the Dysfunctional Attitudes Scale (DAS; Weissman & Beck, 1978), a measure derived from Beck's (1976) cognitive model of depression to measure the presence of attitudes hypothesized to predispose an individual to depression (Kuiper & Olinger, 1989). In previous research, depressed individuals have been found to score higher on the DAS than nondepressed individuals (Gotlib, 1984; Kuiper & Olinger, 1986), and the DAS has been found to predict subsequent depressive episodes (Eaves

4 84 Martin, Kazarian, and Breiter & Rush, 1984; Rholes, Riskind, & Neville, 1985). Our purpose for including the DAS was to determine whether cognitive vulnerability relates to depression in addition to stress among adolescent psychiatric inpatients. Finally, we included a measure of cognitive abilities, the Shipley Institute of Living Scale (SILS; Zachary, 1986) to examine whether these other measures are confounded by intelligence. METHOD Subjects The subjects in this study were 203 adolescent psychiatric inpatients (101 female and 102 male), ranging in age from 12 to 17 (M = 14.8, SD = 1.22). The study included all of the adolescents admitted to the Adolescent Unit of the London Psychiatric Hospital, London, Ontario, from January 1990 to December The sample represents a heterogeneous mix of psychiatric diagnoses. Among the female subjects, the major ICD-9 diagnoses included conduct disturbances (57%), adjustment reaction (18%), depressive conditions (17%), and personality disorders (4%). For the males, predominant diagnoses included conduct disturbances (71%), adjustment reaction (9%), depressive conditions (8%), psychotic disturbances (7%), and personality disorders (5%). Measures Perceived Stress Scale. The PSS (S. Cohen et al., 1983) is a 14-item questionnaire designed to measure the degree to which situations in a subject's life are appraised as stressful, unpredictable, uncontrollable, and overloading. Sample items include: "In the last month, how often have you felt difficulties were piling up so high that you could not overcome them?" and "In the past month, how often have you felt confident about your ability to handle your personal problems?" Responses are given on a 0-4 rating scale ranging from never to very often. S. Cohen et al reported internal consistency coefficients ranging from.84 to.86. In their initial validational research, they found small to moderate correlations between the PSS and life events scales (.17 to.49) and fairly strong correlations with measures of physical symptomatology (.52 to.70) and depression (.65 to.76). In a 2-month prospective study, S. Cohen (1986) found that the PSS predicted physical and psychological symptoms even after symptoms at Time 1 were partialled out.

5 Perceived Stress and Depression 85 Children's Depression Inventory. The CDI (Kovacs, 1981) is a 27-item modification of the Beck Depression Inventory (BDI; Beck, Rush, Shaw, & Emery, 1979) for use with children and adolescents. It is one of the most widely used instruments for the assessment of depression in children and adolescents. An internal consistency alpha of.88 and test-retest reliability over 3 months of.56 were obtained with a large clinical sample of adolescents (Weiss et al., 1991). Previous research has provided evidence of adequate convergent and discriminant validity (e.g., Kazdin, 1981; Carlson & CantweU, 1980) as well as support for the CDI as a screening instrument for depression (e.g., Carey, Faulstich, Gresham, Ruggiero, & Enyart, 1987). Life Event Scale for Adolescents. The LES-A (Coddington, 1984) comprises a list of 50 major life events relevant to adolescents. Sample items include "divorce of your parents," "breaking up with a boy/girl friend," and "failing a grade in school." In this study, the subjects were instructed to indicate which of these events had occurred in their own lives during the past 3 months and during the past year. The events on the LES-A are divided into desirable and undesirable events. In keeping with previous findings that negative rather than positive events are the best predictors of psychological disorder (e.g., Gersten, Langer, Eisenberg, & Orzeck, 1974; Vinokur & Seizer, 1975) and that simple unit weighting yields the most efficient index of stress (e.g., Ross & Mirowsky, 1979; Swearingen & Cohen, 1985), the unit weighted sum of all negative (undesirable) events was used as the measure of life stress. One score was derived for the past year and one for the past 3 months. Coddington (1984) has reported adequate test-retest reliabilities and predictive validity for this measure. Dysfunctional Attitudes Scale. The DAS (Weissman & Beck, 1978) is a 40-item inventory derived from Beck's (1976) cognitive model of depression to measure the presence of attitudes hypothesized to predispose an individual to depression. Sample items include "If I do not do as well as other people, it means I am an inferior human being," and "If others dislike you, you cannot be happy." Adequate internal consistency and test-retest reliabilities have been found (Dobson & Breiter, 1983; Kuiper & Longer, 1989). Shipley Institute of Living Scale. The SILS (Zachary, 1986) is designed to assess general intellectual functioning in adults and adolescents. A total intellectual abilities score is obtained by combining scores from a 40-item vocabulary test and a 20-item test of abstract thinking. Adequate test-retest reliabilities have been obtained, and the measure correlates highly with the WAIS-R.

6 86 Martin, Kazarian, and Breiter Procedure During the first 3 or 4 days after admission to the Adolescent-Unit, patients were asked to complete an informed consent form and a number of self-report measures in random order, including those listed above. The measures were administered by either a psychometrist or ward (nursing) staff, working under the supervision of a psychologist. The test findings were used as an adjunct to treatment planning as well as for research purposes. RESULTS The means and standard deviations of each of the measures used in this study are presented in Table I. Females obtained significantly higher mean scores on the CDI (M = 19.7, SD = 9.99) than did males (M = 15.5, SD = 10.74), t = 2.79, p =.006, indicating that females in this sample were reporting higher levels of depression. This is consistent with the normative study of Weiss et al. (1991), which also found higher CDI scores for females than males among clinical adolescents. Normative research on the CDI with nonclinical children has indicated an expected mean of 9 (SD = 7), with Table I. Means and Standard Deviations of Measures Used in the Study and Significance of t Tests Comparing Male and Female Means t-test Measure Total sample Male Female significance CDI (10.56) (10.74) (9.99) PSS (10.21) (11.14) (8.98) LESA-Yr ns (4.56) (4.97) (4.14) LESA-2 Mo ns (2.90) (2.92) (2.88) DAS (38.80) (37.19) (40.04) SILS (10.57) (10.59) (10.12) Note. CDI = Children's Depression Inventory; PSS = Perceived Stress Scale; LE, SA-Yr. = Life Events Scale for Adolescents, number of negative events over past year; LESA-3 Mo,, number of negative events over past 3 months; DAS = Dysfunctional Attitudes Scale; SILS = Shipley Institute of Living Scale.

7 Perceived Stress and Depression 87 scores above a cutoff of 19 considered clinically significant (Smucker, Craighead, Craighead, & Green, 1986). By this criterion, 53% of the females and 31% of the males were reporting clinically significant levels of depression. These scores are considerably higher than those found by Weiss et al (1991), perhaps due to the fact that their sample included both inpatients and outpatients, whereas the present sample is composed only of inpatients. The mean score on the PSS for the entire sample was 33.8 (SD = 10.21). This is considerably higher than that reported by S. Cohen et al. (1983) for two nonclinical college student samples (M = and 23.67), and somewhat higher than scores found by Hewitt et al. (1992) with their sample of adult psychiatric outpatients (M = 29.07). As in the Hewitt et al. study, the mean PSS score for females (M = 35.3, SD = 8.98) was significantly higher than that for males (M = 32.2, SD = 11.14), t = 2.14, p <.05. An alpha coefficient of.86 was computed for the total PSS, consistent with those found previously by S. Cohen et al. and by Hewitt et al. Mean scores on the LES-A were somewhat higher than those reported by Coddington (1984) for nonclinical adolescents, indicating fairly high levels of life stress reported by this clinical sample. Similarly, the mean DAS scores (M = 139.3, SD = 38.80) were considerably higher than the typical means of 115 to 125 obtained with nonclinical university students (Kuiper & Olinger, 1989). Thus, these inpatient adolescents reported high levels of dysfunctional attitudes representing cognitive vulnerability to depression. The mean total scores on the SILS were significantly higher for females (M = 37.7) than for males (M = 33.3), t = 2.93, p =.004, indicating higher intellectual abilities for females in this sample. None of the variables under investigation were correlated with age in this sample. Table II presents the intercorrelations among all the measures for male and female separately. Significant correlations were found between the PSS and CDI for both male (r =.55, p <.001) and female (r =.48, p <.001). These correlations are similar to those found by Hewitt et al. (1992) with adult psychiatric patients. Sex differences were found in correlations with negative life events. Among females, the number of negative life events, either over the preceding 3 months or the past year, were not significantly correlated with CDI scores or with the PSS. In contrast, for the males, small but significant correlations were found between the CDI and life events over the past year (r =.21, p <.05) and past 3 months (r =.25, p <.05). In addition, for males the PSS was correlated with 1-year (r =.26, p <.01) and 3-month life events (r =.38, p <.001). Thus, for females, major life events do not appear to be an important factor in either their appraisals of stress in their lives or their reported feelings of depression. In contrast, for males, life events do appear to play some role in stress perceptions and symptoms of depression.

8 88 Martin, Kazarian, and Breiter Table ii. Correlations Among Measures Used in the Study for Male and Female Adolescent Inpatients Measure CDI --.55***.21".25*.50*** PSS.48*** --.26**.38***.36*** LESA-Y~ *** LESA-3Mo *** DAS.66***.32*** SILS Note. Correlations for males (n = 102) are shown above the diagonal and females (n = 101) below the diagonal. CDI = Children's Depression Inventory; PSS = Perceived Stress Scale; LESA-Yr. = Life Events Scale for Adolescents, number of negative events over past year; LESA-3 Mo., number of negative events over past 3 months; DAS = Dysfunctional Attitudes Scale; SILS = Shipley Institute of Living Scale. *p <.05. **p <.01. ***p <.001. With regard to dysfunctional attitudes, the DAS was significantly related to the CDI for both female (r =.66, p <.001) and male (r =.50, p <.001). In addition, the DAS was significantly correlated with the PSS (r =.36 for males, r =.32 for females, bothp <.001), but not with negative life events. Thus, cognitive vulnerability appears to be related to both depression and perceived stress, but not to negative life events. Finally, none of these measures were significantly correlated with the SILS, indicating that they are not confounded with intelligence. To determine the relative contribution of perceived stress, negative life events, and dysfunctional attitudes to depression, stepwise multiple regression analyses were computed for male and female separately, entering DAS, PSS, 3-month LESA, and 1-year LESA into the equation to predict CDI scores. In the results for males, both PSS ([3 =.45, t = 5.18, p <.001) and DAS (I3 =.34, t = 3.93, p <.001) accounted for independent variance in CDI scores. Similarly, in the results for females, DAS ([~ =.58, t = 7.38, p <.001) and PSS (13 =.34, t = 4.27, p <.001) both accounted for independent variance in CDI scores. Neither 3-month nor 1-year life events added significantly to the regression for either male or female. Thus, for both male and female, subjective appraisals of stress (PSS) and cognitive vulnerability (DAS) each contributed independently to self-reported symptoms of depression, but major life- events were not related to depression independently of these other two variables. In keeping with the analyses of Hewitt et al. (1992), factor analyses were conducted on the 14 items of the PSS for male and female separately,

9 Perceived Stress and Depression 89 Table IIL Items and Factor Loadings for the Two PSS Factors for Male and Female, as Compared to Those Found by Hewitt et al. (1992) In the last month, how often have you... Male Female Hewitt been upset becausse of something that happened unexpectedly? 2... felt that you were unable to control the important things in your life? 3... felt nervous or "stressed?" dealt successfully with irritating life hassles? 5... felt you were effectively coping with important changes occurring in your life? 6... felt confident about your ability to handle your personal problems? 7... felt that things were going your way? found that you could not cope with all the things you had to do? 9... been able to control irritations in your life? felt that you were on top of things? been angered because of things that happened... outside of your control? found yourself thinking about things that you have to accomplish? been able to control the way you spend your time? felt difficulties were piling up so high that you could not overcome them? Not~ Only factor loadings greater than.40 are shown. using principal components analysis with varimax rotation. For both male and female, scree plots indicated that a two-factor solution was most appropriate, accounting for 50.2% of the variance for males and 47.3% for females. The factor solution was ~ccordingly rotated holding the number of factors constant at two. Factor loadings greater than.40 were considered significant. These factor loadings for male and female are presented in Table III, along with the factor loadings found by Hewitt et al. (1992) for

10 90 Martin, Kazarian, and Breiter comparison purposes. It can be seen that the factor structure was very similar for both male and female. The only differences were that, for females, item 6 loaded on both factors, whereas for males it loaded only on Factor 2; and item 12 did not load on either factor for females but it loaded on Factor 1 for males. In comparing our findings with those of Hewitt et al. (1992), it can be seen that there is considerable convergence in the factor structures. The main difference is that in the Hewitt et al data, Items 10, 12, and 13 did not load on either factor, whereas in our data Items 10 and 13 loaded on Factor 2 for both males and females, and Item 12 loaded on Factor 1 for males. In addition, for Hewitt et al., Item 7 loaded only on factor 1, whereas it loaded on both factors in our data. An examination of the item content suggests that, as with the Hewitt et al. data, the first factor comprises items that reflect general distress, whereas the second factor involves reversekeyed items that appear to reflect perceived ability to cope with current stressful circumstances. In computing factor scores, we used items that loaded consistently on only one factor for both males and females. Thus, Factor 1 (Distress) scores were computed by summing Items 1, 2, 3, 8, 11, and 14. Factor 2 (Perceived Coping) scores were computed by summing Items 4, 5, 6, 9, 10, and 13. Internal consistency analyses revealed an alpha coefficient of.81 for the first factor, and.78 for the second. The correlation between the two factors was.53 for males and.39 for females (both p <.001). This is somewhat higher than that found by Hewitt et al (r =.26), indicating some overlap between the two factors in our adolescent sample. Consistent with the findings of Hewitt et al, females' scores on the distress factor (M = 16.1, SD = 5.21) were significantly higher than males' (M = 13.9, SD = 5.57), t(202) = 2.88, p =.004. Also in keeping with their findings, there was no significant difference on the perceived coping factor between males (M = 13.6, SD = 5.42) and females (M = 14.1, SD = 4.34), t = 0.80, ns. To examine the relationship between the two factors and symptoms of depression, stepwise multiple regression analyses were conducted for male and female separately, entering the two factors to predict CDI scores. For males, both the distress factor (13 =.38, t = 3.91, p <.001) and the coping factor (13 =.26, t = 2.68, p <.01) accounted for independent variance in depression scores. For females, the distress factor accounted for significant variance in CDI scores (13 =.48, t = 5.19, p <.001), whereas the coping factor did not (t = 1.26, ns]. These findings are the reverse of those of Hewitt et al., who found that among adult female psychiatric patients, both factors contributed independently in predicting depression, whereas for males, only the distress factor related to depression.

11 Perceived Stress and Depression 91 Finally, to examine the relative contribution of the two PSS factors, dysfunctional attitudes, and 1-year and 3-month negative life events in relation to depression, stepwise multiple regression analyses were conducted for male and female separately, entering these 5 measures into the equation to predict CDI scores. For males, significant variance in CDI scores was accounted for by both the PSS distress factor (13 =.28, t = 2.70, p <.01) and the perceived coping factor (13 =.25, t = 2.60, p <.01), as well as DAS (13 =.33, t = 3.66, p <.001). Neither life events measure contributed significantly to the equation (t = 1.09 and 1.08 for 1-year and 3-month LESA, respectively, both ns). For females, the distress factor ([3 =.40, t = 5.19, p <.001) and DAS (13 =.56, t = 7.29, p <.001) contributed significantly to variance in CDI, whereas the perceived coping factor (t = 0.08, ns) and the two life events measures did not (t = and for 1-year and 3-month LESA, respectively, both ns). DISCUSSION The purpose of this study was to examine the relative contribution of perceived stress, life events, and dysfunctional attitudes in relation to depression in adolescent psychiatric inpatients, and to investigate the psychometric properties and factor structure of the PSS. The results indicate high levels of perceived stress in this clinical sample as compared to nonclinical college students (cf. S. Cohen et al, 1983) and adult psychiatric patients (cf. Hewitt et al., 1992). The PSS score revealed an adequate level of internal consistency. Also, fairly strong correlations were found between the PSS and self-reported depressive symptomatology. This is consistent with previous research (e.g., Hewitt et al., 1992; Kuiper, Olinger, & Lyons, 1986). In addition, the PSS was not significantly correlated with the Shipley Institute of Living Scale, indicating that it is not confounded by intelligence level. The results of the factor analysis revealed a factor structure very similar to that found by Hewitt et al. (1992) with adult psychiatric patients. Although there appears to be more shared variance between the two factors in this adolescent sample, these data do indicate that the two factors have some distinctiveness from one another. The first factor appears to measure global feelings of distress arising from perceptions that one's life is stressful, unpredictable, uncontrollable, and overloading. The second factor, comprising reverse-keyed items, appears to assess perceptions of an ability to cope with stressors in one's life. As suggested by Hewitt et al. (1992), "perceiving oneself as distressed may involve both a negative affective experience or

12 92 Martin, Kazarian, and Breiter reaction and a perception of one's ability to deal effectively with events or changes" (p. 254). The results indicate some gender differences both in PSS levels and in the correlations with depression. Consistent with the findings of Hewitt et al. (1992), females had significantly higher scores than males on total PSS and on the distress factor, but male and female did not differ on the perceived coping factor. However, contrary to Hewitt et al., in the present study both the distress and coping factors accounted for significant unique variance in depression among males, whereas for females only the distress factor was significantly related to depression. This discrepancy between the two studies suggests that there may be developmental changes from adolescence to adulthood in the ways in which male and female perceive and cope with stress, and in the relative degree to which these factors contribute to symptoms of depression. At the same time, it must also be recognized that these differences may simply be due to the instability of beta weights across samples when correlated predictor variables are used. Of particular interest is the finding that perceived stress appears to play a more important role in depression than do major negative life events, either over the past year or the past 3 months. Although the simple correlations between negative life events and depression were significant for males, negative life events did not make a significant contribution to the variance in depression scores independent of PSS for either male or female. In addition, PSS was uncorrelated with negative life events among females, although these correlations were significant but moderate for males. These findings are consistent with results of previous studies of nonclinical adolescents showing little relationship between major life events and psychological disturbance (e.g., Cohen et al., 1987; Compas, Howell, Phares, Williams, & Giunta, 1989; Nolen-Hoeksema et al., 1992). Our results indicate that although perceptions of stress in one's life are important correlates of depression in adolescent patients, major life events measures do not capture the relevant sources of stress, particularly for females. This is consistent with S. Cohen's (1986) argument that the PSS is sensitive to a wider range of sources of stress than are major life events or daily hassles scales. Further research is needed to identify more precisely the types of problems that contribute to feelings and perceptions of stress in the lives of adolescent patients. In any case, these findings suggest that the PSS is a useful measure for assessing perceptions of life stress in adolescent patients. Another important finding in this. study is that the DAS made a significant unique contribution to the variance in depression, independent of the contribution of either total perceived stress or the two PSS factors. This is consistent with previous findings that cognitive vulnerability factors

13 Perceived Stress and Depression 93 are more important than major life stressors in predicting depression in adolescents (e.g., Nolen-Hoeksema et al, 1992). With regard to the DAS, Kuiper and Olinger (1989) have developed a self-worth contingency model of depression that suggests that individuals who are vulnerable to depression endorse high levels of dysfunctional attitudes, which represent excessively rigid and unrealistic standards for evaluating one's self-worth. In particular, these standards relate to heightened concerns over performance evaluation and excessive need for approval by others. According to this model, when individuals who endorse such attitudes encounter life situations that threaten these cognitive standards for self-worth, they are more likely to suffer a loss of self-esteem and develop symptoms of depression. The findings of the present study indicate that this sort of cognitive vulnerability plays a particularly important role in symptoms of depression experienced by adolescent psychiatric patients. From a clinical perspective, the results of this study suggest several directions for therapeutic intervention with this population. First, therapists need to be careful to identify the relevant sources of stress in adolescents' lives, and to be aware that major life stressors may be less important sources of feelings of distress than their appraisal of their life circumstances. In addition, interventions aimed at helping adolescents cope with stress and depression should focus both on subjective feelings of distress and on perceptions of one's ability to cope with stressful situations. Therapeutic approaches should also be different for the sexes, at least as they pertain to coping factors. In particular, and consistent with clinical observations and the findings of the current study, females tend to present as less able to cope than their male counterparts. To the extent that this view is correct, females may benefit from specific emphasis on developing selfefficacy and mastery. Finally, clinical interventions need to address the underlying cognitive attitudes and attributional styles that seem to be an important component in vulnerability to depression. An important limitation of this study is that we used a cross-sectional methodology and thus could not examine the ability of these measures to predict changes in depression over time. Future research using a longitudinal design is needed to clarify the degree to which perceived stress and dysfunctional attitudes are predictive of depression or merely correlates of depression. In summary, using a heterogeneous sample of male and female psychiatric patients on an inpatient adolescent unit, we were able to replicate the findings of Hewitt et al. (1992) that the PSS is composed of two factors reflecting general distress and perceived inability to cope. The utility of the overall PSS and the two factors in this population is supported by findings of internal consistency and significant correlations with depression scores.

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