Increased amygdala response to masked emotional faces in depressed subjects resolves with antidepressant treatment: An fMRI study

Background: The amygdala has a central role in processing emotions, particu larly fear. During functional magnetic resonance imaging (fMRI) amygdala ac tivation has been demonstrated outside of conscious awareness using masked emotional faces. Methods: We applied the masked faces paradigm to patients with major depres sion (n = 11) and matched control subjects (n = 11) during fMRI to compare amygdala activation in response to masked emotional faces before and after antidepressant treatment. Data were analyzed using left and right amygdala a priori regions of interest, in an analysis of variance block analysis and random effects model. Results: Depressed patients had exaggerated left amygdala activation to all faces, greater for fearful faces. Right amygdala did not differ from contr ol subjects. Following treatment, patients had bilateral reduced amygdala a ctivation to masked fearful faces and bilateral reduced amygdala activation to all faces. Control subjects had no differences between the two scanning sessions. Conclusions: Depressed patients have left amygdala hyperarousol, even when processing stimuli outside conscious awareness. Increased amygdala activati on normalizes with antidepressant treatment. (C) 2001 Society of Biological Psychiatry.