Nomothetic and idiographic symptom change trajectories in acute-phase cognitive therapy for recurrent depression

Abstract

Objective: We tested nomothetic and idiographic convergence and change in 3 symptom measures during acute-phase cognitive therapy (CT) for depression and compared outcomes among patients showing different change patterns.

Method: Outpatients (N = 362; 69% women; 85% White; age M = 43 years) with recurrent major depressive disorder according to criteria in the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; American Psychiatric Association, 2000) completed the Hamilton Rating Scale for Depression (Hamilton, 1960), Beck Depression Inventory (Beck, Ward, Mendelson, Mock, & Erbaugh, 1961), and Inventory for Depressive Symptomatology-Self-Report (Rush, Gullion, Basco, Jarrett, & Trivedi, 1996) on 14 occasions as well as pre/post-CT measures of social-interpersonal functioning and negative cognitive content.

Results: The 3 symptom measures marked the same severity and change constructs, and we offer improved formulas for intermeasure score conversions via their common factor. Pre/post-CT symptom reductions were large (ds = 1.71-1.92), and nomothetic symptom curves were log-linear (larger improvements earlier and smaller improvements later in CT). Nonetheless, only 30% of individual patients showed clear log-linear changes, whereas other patients showed linear (e.g., steady decreases; 20%), 1-step (e.g., a quick drop; 16%), and unclassified (34%) patterns. Log-linear, linear, and 1-step patients were generally similar to one another and superior to unclassified patients post-CT in symptom levels, response and stable remission rates, social-interpersonal functioning, and cognitive content (median d = 0.69).

Conclusions: Reaching a low-symptom "destination" at the end of CT via any coherent "path" is more important in the short term than which path patients take. We discuss implications for theories of change, clinical monitoring of individuals' progress in CT, and the need to investigate long-term outcomes of patients with differing patterns of symptom change.

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Figures

Figure 1

Mean scores on three depressive symptom measures, and their standardized composite, by assessment. BDI = 21-item Beck Depression Inventory (21 items). HRSD = 17-item Hamilton Rating Scale for Depression. IDS-SR = 30-item Inventory for Depressive Symptomatology--Self-Report. Intake = first pre-treatment assessment. W1-12 = assessment at cognitive therapy weeks 1-12. Post = post-treatment assessment.

Figure 2

Mean symptom scores for groups of patients showing three a priori patterns of depressive symptom change. Intake = first pre-treatment assessment. W1-12 = assessment at cognitive therapy weeks 1-12. Post = post-treatment assessment. The one-step line shows average Intake and Post scores, as well as average scores immediately before and after the median step between W3-W4; dotted lines indicate interpolation of remaining scores because the pre-/post-step durations vary among patients.

Figure 3

Mean symptom scores for group of patients identified by growth mixture modeling. Intake = first pre-treatment assessment. W1-12 = assessment at cognitive therapy weeks 1-12. Post = post-treatment assessment. All model coefficients significant at p < .01 in predicting symptoms y at assessment t numbered 1-14. No change group: yt = 58.83. Linear change group: yt = 53.81 - 1.16t. Quadratic change group: yt =53.42 - 4.35t + 0.20t2. Cubic change group: yt = 52.50 - 10.31t + 1.10t2 - 0.04t3.