Parsing the components of the psychomotor syndrome in schizophrenia.

OBJECTIVE: Catatonia, extrapyramidal signs, psychomotor slowing, and (motoric) neurological soft signs are well-known psychomotor symptoms in schizophrenia. This study aims at investigating the interrelations between these symptoms. In addition, associations between psychomotor symptoms, clinical symptoms, and cognitive functioning will be studied.
METHOD: An extensive test battery containing psychomotor (Bush Francis Catatonia Rating Scale; St Hans Rating Scale; Salpêtrière Retardation Rating Scale; Neurological Evaluation Scale) and clinical (Positive and Negative Syndrome Scale; Calgary Depression Scale) rating scales as well as instrumental psychomotor tests (Line Copying Task; Finger Tapping Task) and cognitive tasks (Symbol Digit Substitution Test; Stroop Colour Word Test; Continuous Performance Test; Letter Number Sequencing) was administered to a sample of 124 patients with schizophrenia or schizoaffective disorder.
RESULTS: Correlational analyses showed that two clusters emerge from our data: first, a psychomotor poverty cluster referring to the interrelations between catatonia, parkinsonism, psychomotor slowing, and negative symptoms; second, a cluster containing motoric neurological soft signs, which were found to be correlated with cognitive functioning.
CONCLUSION: Psychomotor abnormalities are highly prevalent phenomena in schizophrenia that have to be considered as a heterogeneous construct. However, longitudinal and neurobiological research is needed to further explore the precise nature of the interrelations found in this study.