Timing of movements in depressed patients and healthy controls

Psychomotor disturbances are fundamental psychopathological features of major depression and observable components of behaviour. Human behaviour is segmented into action units with duration of a few seconds due to central nervous motor processing. Timing may depend on cognitive and emotional functions which are affected in depression. Therefore, time structure of action units in depressed patients was compared to healthy controls.

Included were patients with major depression and melancholic features. Upper limb movements (total n = 566) of depressed patients and matched controls were evaluated using videotaped interviews and frame-by-frame analysis with a temporal resolution of 40 ms.

Behaviour of depressed patients in interview sessions was organised in action units with a narrow time span of only a few seconds. Single, non-repetitive action units were significantly shorter (median = 1.20 s) and repetitive units longer (median = 4.92 s) in patients compared to controls (median = 2.08 and 2.96, respectively).

Behaviour in interview sessions might differ from activities of daily living.

Altered temporal segmentation of movements appears to be an observable, measurable sign of melancholic depression and may allow further insights in pathophysiological dysfunctions of the disease. Clinical implications of these motor changes for differential diagnosis, course and treatment of depression are discussed and need further evaluation.