Neurological Signs and Involuntary Movements in Schizophrenia: Intrinsic To and Informative on Systems Pathobiology

Abstract

While it has long been considered whether the pathobiology of schizophrenia extends beyond its defining symptoms to involve diverse domains of abnormality, in the manner of a systemic disease, studies of neuromotor dysfunction have been confounded by treatment with antipsychotic drugs. This challenge has been illuminated by a new generation of studies on first-episode schizophrenia before initiation of antipsychotic treatment and by opportunities in developing countries to study chronically ill patients who have remained antipsychotic naive due to limitations in provision of psychiatric care. Building from studies in antipsychotic-naive patients, this article reviews 2 domains of neuromotor dysfunction in schizophrenia: neurological signs and involuntary movements. The presence and characteristics of neurological signs in untreated vis-à-vis treated psychosis indicate a vulnerability marker for schizophrenia and implicate disruption to neuronal circuits linking the basal ganglia, cerebral cortex, and cerebellum. The presence and characteristics of involuntary movements in untreated vis-à-vis treated psychosis indicate an intrinsic feature of the disease process and implicate dysfunction in cortical-basal ganglia-cortical circuitry. These neuromotor disorders of schizophrenia join other markers of subtle but pervasive cerebral and extracerebral, systemic dysfunction, and complement current concepts of schizophrenia as a disorder of developmentally determined cortical-basal ganglia-thalamo-cortical/cerebellar network disconnectivity.

Characterization of the Deficit Syndrome in Drug-Naive Schizophrenia Patients: The Role of Spontaneous Movement Disorders and Neurological Soft Signs

“…8,20 Ratings of SMD and NSS were substantially correlated, which supports their consideration as partially overlapping subdomains within a more broad neurological domain of schizophrenia. 37 Overall, neurological ratings, excepting akathisia, tended to be consistently related to deficit schizophrenia and to deficit features in the whole population of schizophrenia patients.…”

“…[3][4][5][6][7] Neurological impairment in schizophrenia is now recognized to comprise two domains: spontaneous movement disorders (SMD) and neurological soft signs (NSS), which are thought to be highly informative on the neurobiological substrate of the illness. 8 Neurological dysfunction has been a major focus of research in validating the deficit/nondeficit distinction and a number of reports have noted that patients with deficit/negative schizophrenia are more impaired than their nondeficit/nonnegative counterparts regarding extrapyramidal movement disorders [9][10][11][12][13] and NSS. 3,6,12,14,15 Most of these studies, however, were conducted in chronic and medicated patients.…”

Motor Symptoms and Schizophrenia

“…Recent reviews have addressed the nosological problems concerning catatonia [6,7,8], the meaning of abnormal involuntary movements and neurological soft signs (NSS) in schizophrenia [9,10,11], psychomotor slowing [12], and motor deficits or neurological abnormalities in antipsychotic naïve schizophrenia patients [10,13,14]. Since these reviews focused on specific aspects of motor deficits or on special populations, a comprehensive view of motor phenomena is difficult to develop, since the descriptions, definitions, and interpretations vary largely with the conceptual frameworks [15].…”

Less Structured Movement Patterns Predict Severity of Positive Syndrome, Excitement, and Disorganization

“…5 Motor behavior is altered in schizophrenia, including specific motor disturbances and general motor activity levels. 6,7 Indeed, schizophrenia patients engage less frequently in sports, 8,9 but more in sedentary behaviors, 9 and have less activity during leisure time than the average population. 10 Activity monitoring using actigraphy allows an objective assessment of schizophrenia motor behavior.…”