Objective: Alterations of motor phenomena are observable clinical phenomena of depressed patients. In addition to cognitive and emotional disturbances, motor dysfunctions are frequent psychopathological features which relate to neurobiological mechanisms of depression. Specific functions of various motor domains, pathophysiological concepts, and relevance of motor functions for diagnosis and prognosis of depression are summarized.
Methods: The contemporary literature regarding clinical and research aspects of differential diagnosis, treatment response and pathophysiology as well as the current knowledge regarding objective measures of motor signs in depression are reviewed.
Results: Alterations in motility (gross motor activity), locomotion, gestures, mimic, speech characteristics, and tremor are relevant for diagnosis, therapy and prognosis of depression. A large body of literature exists regarding qualitative, indirect measures of motor phenomena and quantitative analysis of motility. Only few unidimensional studies exist in respect to locomotion, gait and tremor in depression. The low correlation between physiological and clinical features may be due to methodological issues. Whereas most publications investigate motor functions indirectly using different functional coding and classification systems, only few studies report direct, physical, characteristics (kinematics) of motor phenomena in depression.
Conclusions: Existing concepts do not clarify the relation of psychological and somatic components of motor signs. Agitation and retardation should be analyzed as multidimensional and independent variables. New psychometric instruments for documentation of motor phenomena in depression need further evaluation. Application of current technology and quantitative movement analysis may yield further insights in pathophysiological mechanisms and therapeutic strategies and represent important aspects of neurobiological research of depression.