Facial electromyography in depression. Subgroup differences.

To study whether facial electromyographic (EMG) activity during affective imagery differed between normal subjects and depressive subtypes, we evaluated EMG responses in 29 normal controls, 37 endogenously depressed patients, and 26 nonendogenously depressed patients. Different imagery states produced more distinctive EMG patterns in normal controls than in depressed patients. Patients with endogenous depression had EMG levels that differentiated them from normal subjects and had significantly greater absolute values than the nonendogenous group in corrugator happy and corrugator sad imagery trials. Intensity of sad and happy imagery, age, and severity of depression did not systematically correlate with EMG activity among depressive subtypes.