Objective: To study the correlation of personality traits measured by the Temperament and Character Inventory (TCI) with the prognosis of major depressive disorder in patients treated with either fluoxetine or short-term psychodynamic psychotherapy in a randomized comparative study.

Method: 35 patients with DSM IV-defined major depressive disorder of mild or moderate severity were randomized to receive either short-term psychodynamic psychotherapy or fluoxetine treatment for 16 weeks. Prior to beginning of the therapy, patients were assessed with TCI. The Hamilton Depression Rating Scale (HDRS) was used as the outcome measure completed at the baseline and follow-up at 4 months.

Results: In the combined group (n=35), Harm Avoidance was associated with the severity of the depression measured by the HDRS at the baseline (P=0.01) and baseline Self-Directedness with the HDRS at 4 months follow-up (P=0.03). In the fluoxetine treatment group, Reward Dependence (P=0.03), Self-Directedness (P=0.01) and Cooperativeness (P=0.02) at the baseline associated with HDRS at 4 months follow-up. No statistically significant associations between personality traits and depression scores at the follow-up were found in the patients treated with psychotherapy.

Conclusion: In this whole cohort of depressive patients, baseline high Self-Directedness predicted higher depression scores after 4 months of treatment. In the fluoxetine treatment group, subjects with high baseline Reward Dependence, Self-Directedness or Cooperativeness were likely more severely depressed at the 4 months follow-up. We suggest that associations between personality traits and remaining depressive symptoms after 4 months treatment with fluoxetine could be caused by the potential differences in the placebo effect.