Intraindividual dimensional structure and prediction of symptoms from cognitions in adults being treated for comorbid mood and anxiety disorders
Green, Katherine Michelle
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Cognitive models of depression and anxiety posit that maladaptive beliefs and schemas about the self, world and future play an important causal role in a patient's distress and dysfunction (Clark & A. Beck, 1999). Cognitive therapy manuals (e.g., A. Beck et al., 1979; J. Beck, 1995; Persons, 1989) stress the importance of assessing idiosyncratic beliefs/schema and using this formulation to guide treatment decisions. However, most research testing the cognitive model has used cross sectional aggregate designs instead of the idiographic methodology necessary to determine the role of idiosyncratic beliefs in symptom maintenance. The present study investigated the intraindividual dimensional structure of symptoms and cognitions, and their relationship in adults with comorbid depression and anxiety disorders. The study used a multivariate, replicated, single-subject, repeated-measures design (Jones & Nesselroade, 1990) and an idiographic assessment methodology. Four adults completed a l2-week cognitive-interpersonal formulation-based treatment. Concurrently, each completed daily measures of idiographic items developed from a semi-structured assessment interview as well as items based on standardized outcome measures. Results indicated that one patient demonstrated significant improvement m most standardized measures while the remaining three showed decreases in severity of depression or anxiety. Notably, some individualized measures demonstrated greater sensitivity to change than standardized measures. Interview-based idiographic cognition items contributed strongly to intraindividual cognition factors assessing idiosyncratic beliefs. Time-series regression analyses indicated that these idiosyncratic maladaptive beliefs were important in the maintenance and topography of patient distress. The strength of prediction ranged from R^2 = .05 to .90, with the majority being R^2 > .45. Furthermore, many symptoms were predicted by cognitions on previous days, with lagged relationships present for 11 of the 14 symptom factors (across the four patients). Finally, cognitive-behavioral interpersonal scenarios, developed from the clinical interview, predicted symptom factors incrementally above that of the cognition factors. Results have significant implications for clinical cognitive theory and for assessing and treating patients with comorbid disorders.