Validation Study of Tripartite Model of Anxiety and Depression in Children and Adolescents: Clinical Sample in Korea

The relationship between depression and anxiety disorders has been the focus of attention for many mental health clinicians and researchers. Interest in this issue stems primarily from the high degree of comorbidity and correlation between these two conditions. Epidemiological studies have reported that the comorbidity rates between depression and anxiety disorders are from 30% to 75% (1, 2), and the correlation measured by self-reports has been placed between 0.50 and 0.80. The findings of research conducted in the 1970s and 1980s can be thought of as fitting into three categories: a) anxiety and depression differ quantitatively (i.e., unitary model); b) anxiety and depression differ qualitatively (i.e., dual model); c) combined anxiety and depression differ both quantitatively and qualitatively from either pure anxiety or pure depression (3). However, researchers have gradually begun to realize that the dispute over these three concepts is an unnecessary and unproductive one (4). In other words, it has been realized that it will be more effective and productive to determine exactly what the similarities and differences of anxiety and depression are, rather than debating whether the two conditions are quantitatively or qualitatively different. On the basis of this background, Clark and Watson (5) suggested a new concept, now commonly referred to as the tripartite model of anxiety and depression.

Clark and Watson hypothesized three relatively independent factors, positive affect (PA), negative affect (NA), and physiological hyperarousal (PH). They proposed that anxiety and depression are both characterized by the nonspecific distress of NA, whereas anxiety and depression each feature their own unique factors, high PH (anxiety) and low PA (depression). The tripartite model has rapidly received extensive empirical support (6, 7). This model, which was initially developed from adult empirical data, has been applied to both child and adolescent samples, and, in the past 15 yr, ever-increasing efforts have focused on the validity of the tripartite model of anxiety and depression in these younger age groups (8, 9).

For example, Joiner et al. (10) selected NA, PA, and PH construct items from the Children's Depression Inventory (CDI) and the Revised Children's Manifest Anxiety Scale (RCMAS) on the basis of tripartite model, and these items were completed by child and adolescent inpatients. Exploratory factor analysis produced three factors, NA, PA, and PH, in parallel with the tripartite model. This represents the very first support for the tripartite model of child and adolescent anxiety and depression. Thereafter, Chorpita et al. (11) provided further empirical support for the tripartite model, using confirmatory analysis in a study involving community youths. In addition, several new scales for the evaluation of child emotions, and the examination of tripartite model constructs such as Positive Affect and Negative Affect Schedule for Children (12) and Affect and Arousal Scale (13) have been developed, thus continuously providing further empirical support for the model.

To date, however, tests of the tripartite model have been conducted principally with Caucasian youths in America. To the best of our knowledge, only two studies of this subject with community adolescents have been conducted outside of America and these only provided partial empirical support (14, 15). As racial and ethnic differences exist in the symptom presentations of psychiatric disorders (16), more cross-cultural validation studies for tripartite model of anxiety and depression are necessary to broaden its application. Therefore, the objective of the present study was to validate the tripartite model of emotion to clinical samples in Korea. In order to compare our results with those of previous tests, we used items which had been logically selected by Joiner et al. (10). We also attempted to determine how accurately anxiety and depression could be differentiated using the selected items, on the basis of the tripartite model.

The result of this study, which was consistent with the findings of previous studies, reported that the model fit index of the three-factor structure was significantly superior to that of all of the other models. In addition, using the items logically selected from the CDI and RCMAS on the basis of tripartite model, we found there to be no significant differences between the anxiety and depression groups with regard to NA. However, the group with anxiety disorders showed more physiological hyperarousal than the group with depression. On the contrary, the group with depression showed lower in positive affect than the group with anxiety disorders. In addition, the findings of discriminant analysis indicated that the correct rate at which anxiety disorders could be differentiated from depression using the NA, PA, and PH constructs was higher than when using the whole scales, CDI and RCMAS. These findings provide further evidence supporting the validation of the tripartite model of emotion in a clinical sample of patients suffering from anxiety and depressive disorders.

To date, the validity of the tripartite model in children and adolescents has been verified by the results of prior empirical studies for a decade (8). However, almost all studies on this subject have been done in America, primarily with Caucasian youths. The results of this study, however, serve to broaden the application of the tripartite model to diverse ethnic and cultural groups.

Although the overall results of this study tend to support the tripartite model, three factors in this sample were highly correlated with one another, in contrast with Clark and Watson's hypothetical explanation (5) that the tripartite factors are orthogonal dimensions.

Several explanations are possible for these unexpected results. The first explanation involves the sample used in this study. The subject group in this study was comprised of children and adolescents, all of whom had anxiety and depressive disorders which were sufficiently severe enough to warrant a visit to the department of psychiatry in a general hospital. Comorbidity with anxiety and depression is a very common phenomenon. Thus, it is not surprising that patients with either anxiety or depression also have increased tendencies toward the other symptoms, although these tendencies are not normally sufficiently severe to constitute additional diagnoses.

A second explanation concerns the scales used in this study, CDI and RCMAS. It has been repeatedly proposed that both the CDI and the RCMAS possess low discriminant validity, and are only used as measurements of general distress and NA, due to the fact that they were developed in the absence of a theoretical background (23, 24). The NA, PA, and PH items used in this study were selected from these scales, and thus there might be a high degree of overlap among the tripartite constructs, even though the items had been theoretically selected. By way of contrast, other investigations employing PANAS-C and AFARS, which were specifically designed to assess the tripartite model, indicated only a few correlations among factors, which is consistent with Clark and Watson's hypothesis (5).

The third explanation is related to cultural differences. It is suggested that patients in non-Western cultures report somatic symptoms and deny psychological symptoms more frequently than patients in Western countries (25). In Korea, based on the traditional Confucian background of the culture, the direct expression of emotions is fairly restricted. In other words, the inhibition of emotional expression is a Korean cultural characteristic. Therefore, Koreans exhibit a tendency to express their negative feelings as somatic complaints. Considering Korean culture, it might be inferred that somatic symptoms tend to be more strongly associated with negative emotions, including anxiety and depressive symptoms, than in any other cultures, particularly Western cultures. The Korean cultural context may explain why the correlations of three constructs are higher than was found in the prior studies, which were conducted primarily in America, and in Clark and Watson's hypothesis; thus, cultural background should be considered to some degree when applying the tripartite model to other cultures. In order to resolve issues regarding the relationships between the three constructs in the tripartite model, three possibilities might be considered. Additional research with multiple scales, and in other countries, will be required for a solid solution.

To the best of our knowledge, this study is the first to investigate the tripartite model of anxiety and depression in Asia. The findings from this study serve to expand the applicability of the tripartite model. However, it should be noted that this study suffers from several inherent methodological limitations. Structured interviews for diagnosis were not conducted in this study, although semi-structured clinical interviews were conducted by a psychiatrist. Besides, due to the fact that we used only children and adolescents' self-reports as an informant, we abrogated the benefits which would have been generated from the use of multiple informants. In addition, it should be noted that it was one of the limitations that the subject number of anxiety disorders was relatively small in this study. Considering the limitations of this study, though, more research with diverse cultures will be required in order to facilitate the application of the tripartite model in the future.