Personality and outcome in individuals with treatment-resistant depression – exploring differential treatment effects in the Tavistock Adult Depression Study (TADS)

OBJECTIVE: Although research over the past decades has investigated the impact of the personality dimensions of dependency and self-criticism on treatment outcome, little is known of how these personality features influence responsiveness to treatment in patients with severe, chronic forms of depression. METHOD: The present study uses data from the Tavistock Adult Depression Study (TADS), a randomized controlled trial investigating the effectiveness of long-term psychoanalytic psychotherapy (LTPP) compared with treatment as usual (TAU) for individuals diagnosed with treatment-resistant depression. Patients were rated with the Anaclitic Introjective Depression Assessment Q-sort, which distinguishes between two more maladaptive (Submissive and Dismissive) and two less maladaptive (Needy and Self-Critical) subdimensions of dependent or anaclitic and self-critical or introjective depression. Multilevel modeling was used to compare individuals’ growth curves of depression severity as measured by the Hamilton Rating Scale for Depression over the 18-months treatment period and two-year follow-up. Rates of clinically significant change were also determined. RESULTS: As expected, depressed patients with more maladaptive dependent and self-critical features did not benefit from LTPP or TAU. Patients with less maladaptive self-critical features benefitted from both LTPP and TAU, while those with less maladaptive dependent features showed considerable gains from LTPP but not from TAU, with medium to large effect sizes. CONCLUSIONS: Findings of this study are consistent with existing research suggesting the need to modify and tailor treatments in accordance to individuals’ pre-treatment personality features. Given the time and cost-intensive nature of longer-term treatment, this may be particularly important in patients with treatment-resistant depression