Do antidepressants change personality?--a five-year observational study

Whether antidepressants influence personality is a major clinical and societal issue due to their widespread use. In an observational study, we investigated whether depressive patients' neuroticism and extraversion scores covary with antidepressant pharmacotherapy, and if so, whether this remains significant after accounting for depressive or anxiety symptoms.

Major depressive disorder patients (N=237) were interviewed at up to four time-points in a five-year prospective longitudinal study. Changes in neuroticism plus extraversion scores were compared with changes in antidepressant pharmacotherapies and depressive plus anxiety symptoms to uncover any covariation between them. Autoregressive path models were used to examine this covariation at the sample level. Within-subject change was estimated using a random-effects latent change model.

Significant covariation is present in the change trajectories between personality scores and depressive symptoms; declining depression scores were associated with rising extraversion and declining neuroticism. Although the personality scores of many patients changed significantly over the five-year study, none of these changes were associated with changes in antidepressant pharmacotherapy.

The study covered only two dimensions of personality. Single drug-specific analysis could not be done. Antidepressant blood levels were not measured.

No evidence emerged for significant covariation of antidepressant pharmacotherapy with neuroticism or extraversion scores. By contrast, changes in both personality dimensions were associated with changes in depressive symptoms, those in neuroticism also in anxiety symptoms. If antidepressants influence these personality dimensions, the effect size is likely markedly smaller than that of the disorders for which they are prescribed.