Emotional blunting with bupropion and serotonin reuptake inhibitors in three randomized controlled trials for acute major depressive disorder.

Background: Emotional blunting is theorized to be an adverse effect of antidepressants, particularly serotonin reuptake inhibitors, but this has not been firmly established. Another possibility is that emotional blunting represents a residual depressive symptom.

Methods: We analyzed data from adult outpatients with acute major depressive disorder who participated in three 8-week randomized controlled trials. Trials 1 and 2 were pooled (venlafaxine, n = 378; bupropion, n = 389; placebo, n = 383) and Trial 3 (escitalopram, n = 254; bupropion, n = 260) was analyzed separately. Emotional blunting was measured with the "inability to feel" item from the Montgomery-Åsberg Depression Rating Scale.

Results: Emotional responsiveness improved, on average, in all treatment groups. Only a minority of participants (≤6 %) experienced more emotional blunting post-treatment, compared to baseline, with no significant differences between treatment groups, although roughly 20-25 % continued to report an inability to feel normal emotions at the final assessment. In Trials 1 and 2, emotional blunting was associated with poorer outcomes in terms of depressive symptoms, suicidal ideation, and sexual function, but these correlations were nearly identical in the placebo group.

Limitations: The trials were short and cannot speak to the possibility of emotional blunting from long-term treatment. Emotional blunting was measured with a single item.

Conclusions: The study medications did not significantly decrease emotional responsiveness, and there was no evidence that emotional blunting mediated treatment response. In acute treatment, emotional blunting may be better conceptualized as a residual symptom than as an adverse drug effect.