What is the nonverbal communication of depression? Assessing expressive differences between depressive patients and healthy volunteers during clinical interviews.

It is unclear if individuals with Major Depressive Disorder (MDD) present different nonverbal behavior (NVB) compared with healthy individuals, and also if depression treatments affect NVB. In this study, we compared the NVB of MDD subjects and healthy controls. We also verified how MDD subjects' NVB is affected by depression severity and acute treatments. We evaluated 100 MDD outpatients and 83 controls. We used a 21-category ethogram to assess the frequency of positive and negative NVB at baseline. MDD subjects were also assessed after eight weeks of treatment (pharmacotherapy or neuromodulation). We used the Wilcoxon signed-rank test to compare the NVB of MDD subjects and controls; beta regression models to verify associations between MDD severity and NVB; the Shapiro-Wilk test to verify changes in NVB after treatment; and logistic regression models to verify NVB associated with treatment response according to the Hamilton depression rating scale. Compared with controls, MDD subjects presented higher levels of six negative NVB (shrug, head and lips down, adaptive hand gestures, frown and cry) and lower levels of two positive NVB (eye contact and smile). MDD subjects' NVB was not associated with depression severity, and did not significantly change after depression treatment. Treatment responders showed more interpersonal proximity at baseline than non-responders. Our ethogram had no measure of behavior duration, and we had a short follow-up period. MDD subjects have more negative and less positive social NVB than controls. Their nonverbal behavior remained stable after clinical response to acute depression treatments.