| dc.description.abstract | The tripartite model by Watson and Clark (1991) represents one way to conceptualize symptoms of depression and anxiety, which has received encouraging empirical support from factor analytic, pharmacological and other biological research. This model categorizes symptoms of depression and anxiety into symptoms of general distress / negative affect (shared by depression and anxiety), symptoms of anhedonia / low positive affect (specific to depression) and symptoms of somatic anxiety (specific to anxiety).
The present study used the tripartite model (Clark and Watson, 1991) as a framework for investigating treatment response in moderate to severe major depression. Data were obtained from a two-site comparison of cognitive behavior therapy (CBT) versus pharmacotherapy (PT) in the treatment of depression and the prevention of subsequent relapse (DeRubeis et al., 2005; Hollon et al., 2005). The current sample consisted of 181 depressed outpatients who were randomly assigned to sixteen weeks of either CBT (N = 62) or PT (N = 119) with paroxetine as the primary medication.
For the assessment of the symptom dimensions ANH, GD, and SA, items were selected from standard depression and anxiety symptom measures. Confirmatory factor analysis found support for distinct, yet correlated, factors consistent with the tripartite dimensions. Longitudinal growth curve modeling found support for differential treatment effects of CBT versus PT with respect to the pattern of change in the tripartite dimensions. Compared to CBT, paroxetine provided a more rapid change in GD early in treatment. In fact, most of the change in GD and SA occurred within the first eight weeks of treatment, whereas CBT reduced GD and SA more gradually. No such treatment difference was found for ANH symptoms which showed similar patterns of change with PT and CBT. Further, the presence of comorbid anxiety disorders at intake was associated with higher pre-treatment levels of GD (and to a lesser extent SA), but not ANH. Results provide further support the usefulness of the tripartite model in the development of treatment strategies, which most effectively target specific symptoms groups of depression. | |
