Reduced facial expression and social context in major depression: discrepancies between facial muscle activity and self-reported emotion.

The expression of emotion is determined by emotion and the presence and absence of others, i.e. social context. The present study examined social context differences in facial muscle activity and self-reported emotion of 11 major depressed and 11 non-depressed patients. Subjects were asked to imagine happy and sad situations with and without visualizing other people. Facial muscle activity over the brow and cheek region was reduced in depressed compared to non-depressed patients during happy and sad imagery whereas self-reported emotion showed no group differences. In both subject groups, happy imagery induced increased smiling and self-reported happiness whereas sad imagery induced increased frowning and self-reported sadness. Smiling and self-reported happiness were increased during happy-social compared to happy-solitary imagery in both groups. In contrast, frowning showed a lack of social context differences, although self-reported sadness was increased during sad-social vs. sad-solitary imagery in both groups. Reduced facial muscle activity in depression may indicate psychomotor retardation whereas the lack of social context differences in frowning may suggest social disengagement and an inhibition of sad facial expression in the presence of others.