Correlations of Cerebellar Function with Psychotic Symptoms and Cognitive Function in Schizophrenic Patients

ABSTRACT

OBJECTIVES: There is increasing evidence that the cerebellum plays an important role in cognition and psychiatric symptoms as well as motor coordination. The concept of cognitive dysmetria has been making cerebellar function in schizophrenia the focus of current studies. In other words, disruption in the cortico-cerebellum-thalamic -cortical circuit could lead to disordered cognition and clinical symptoms of schizophrenia. The purposes of this study were to determine cerebellar dysfunction in male schizophrenic patients semiquantitatively with ICARS and to investigate the clinical and cognitive correlates of ICARS in patients. METHODS: We compared the scores of cerebellar neurologic sign using ICARS in 47 male patients with a DSM-IV-TR diagnosis of schizophrenia with 30 gender and age-matched healthy control subjects. The semiquantitative 100-point ICARS consists of 19 items divided into 4 unequally weighted subscores posture and gait disturbances, kinetic functions, speech disorders and oculomotor disorders. All subjects were also assessed with cognitive function test. Cognitive functions were evaluated by Korean-Mini Mental Status Examination(K-MMSE), Verbal fluency test, and Clock drawing test. The patients were administered Korea version of Positive and Negative Symptom Scale(K-PANSS) to assess the symptom severity. RESULTS: Schizophrenic patients had significantly higher scores on the ICARS than control subjects with posture and gait disturbances, kinetic functions, and oculomotor disorders. They also showed more significant impairments in cognitive function tests than control subjects. There was a significant correlation between ICARS and negative symptoms of patients. In cognitive function test, Clock drawing test was significantly associated with negative symptoms. In addition, Clock drawing test was negatively correlated with the total score of ICARS. CONCLUSION: In this study, we confirmed that schizophrenic patients have significant impairments in cognitive and cerebellar function, and that those were related with negative symptoms of schizophrenic patients. These results support a role of the cerebellum in schizophrenia. It is meaningful that we used a structured, and reliable procedure for rating neurological soft signs, ICARS. We hope that future prospective studies using a similar design help that rate of neurological sign should have been visible with the progression of illness.