Motor Symptoms of Schizophrenia
Schizophrenia is typically conceived as an illness characterized by positive, negative, and cognitive symptoms. However, most schizophrenia patients also display a wide range of symptoms characterized by aberrant motor functioning. Symptoms of schizophrenia that fit this description are catatonic features, the motoric neurological soft signs (NSS), extrapyramidal symptoms (EPS), psychomotor slowing, and reduced motor activity.
Catatonia
Catatonic symptoms form a heterogeneous group of motor, emotional, and behavioral symptoms. Mostly in line with historical reports, several recent studies demonstrate a prevalence of the catatonic features in 5–32% of schizophrenia patients (1, 2). Although the incidence of catatonia in schizophrenia may have decreased somewhat, the syndrome is still highly prevalent but often underdiagnosed (2).
Neurological Soft Signs
Neurological soft signs are a heterogeneous cluster of subtle neurological signs that are generally divided into four sub-categories: sensory integration, primitive reflexes, motor coordination, and sequencing of complex motor acts, the latter two being considered “motoric” NSS (3). NSS have been demonstrated in up to 97 and 100% of neuroleptic naive and medicated first-episode patients, respectively (1).
Psychomotor Slowing
Psychomotor slowing refers to the slowing of various motor processes such as gross (e.g., gait) and fine motor (e.g., writing) movement, speech, and facial expression. Our group conducted a series of studies in which impairments in different aspects of psychomotor functioning were slowed, including planning, initiation, and execution of movements (4, 5).
Several studies assessed the amount of motor activity by means of actigraphy, which consistently demonstrated reduced motor activity levels in schizophrenia patients (2, 6). This reduction in spontaneous motor behavior was associated with negative symptom severity (7, 8).
Extrapyramidal Symptoms
Akathisia, Parkinsonism, dyskinesia, and dystonia are considered EPS. Although these clinical features are most persistently linked to antipsychotic pharmacotherapy, there is growing consensus that the use of antipsychotic medication is not the main cause but a contributing factor to motor abnormalities in schizophrenia (9). In a systematic review (10), a median rate of 9% of spontaneous dyskinesia and a median rate of 17% of spontaneous Parkinsonism was reported in antipsychotic-naive first-episode patients, thus positioning EPS as highly prevalent intrinsic symptoms of schizophrenia. Spontaneous Parkinsonism and abnormal involuntary movements are also found at increased frequencies in unaffected first degree relatives of schizophrenia patients (11)