Cerebellar substructures and neurological soft signs in first-episode schizophrenia.

A subtle impairment of motor coordination and sensory integration functions is frequently found in schizophrenia. Clinically these deficits present as neurological soft signs (NSS). Because of its crucial role in motor function, control of muscle tone and equilibrium, the cerebellum is likely to be involved in the appearance of NSS. Magnetic resonance imaging (MRI) was performed in 30 patients with first-episode schizophrenia - all treated with atypical neuroleptics - and 21 healthy controls. NSS were rated on the Heidelberg Scale. By manual tracing, the cerebellum was divided into the following subregions bilaterally: anterior lobe, superior posterior lobe, inferior posterior lobe, and corpus medullare, respectively. Volumetric measures were compared between the two groups and related to NSS scores. NSS scores were significantly higher in patients than in controls. Cerebella of patients were significantly smaller with atrophy pronounced in the corpus medullare bilaterally. In the patients' group, higher NSS scores were found to be related to reduced volumes of the posterior lobes of the cerebellum. In contrast, no significant associations between NSS scores and cerebellar subregions in healthy subjects arose. Our findings support the hypothesis of cerebellar involvement in schizophrenia and indicate that alterations in distinct cerebellar regions are related to NSS.