Segmentation of behavior and time structure of movements in depressed patients

Psychomotor alterations are fundamental psychopathological features of major depression and observable components of behavior. Human behavior is segmented into action units with a duration of a few seconds. Cognitive and emotional dysfunctions in depression may affect the time structure of movements. Therefore, upper limb movements (total n = 707) of depressed patients and matched healtyh controls were studied using videotaped interviews and frame-by-frame analysis with an accuracy of 40 ms. Both groups displayed a similar temporal distribution, but nonrepetitive action units were significantly shorter (median = 1.16 s) and repetitive units longer (median = 4.92 s) in depressed patients compared to controls (median = 1.93 and 3.01, respectively). Movement alterations were related to anhedonia and subjective severity of depression. Altered time structure of movements represents an observable psychopathological sign and may be relevant for pathophysiological and behavioral aspects in depression.