Neurological Soft Signs and Corpus Callosum morphology in schizophrenia

Neurological Soft Signs (NSS) have been found to be more prevalent in schizophrenic patients. A breakdown in intracortical functional connectivity, including interhemispheric communication, has been suggested in the pathogenesis of schizophrenia. Indeed, problems with interhemispheric information transfer via the Corpus Callosum (CC) have been documented in schizophrenics. Our study goal was to relate NSS to CC morphology.

CC Magnetic Resonance Imaging (MRI) measurements were collected from 29 right-handed male schizophrenia inpatients. NSS were evaluated employing the Neurological Evaluation Scale (NES). We examined the scores obtained from the NES total and the three NES subscales: Integrative Sensory Function, Motor Coordination, and Sequencing Of Complex Motor Acts. We compared CC morphology of patients with "high" NSS with that of patients with "low" NSS. Correlation analyses were performed to further clarify the relationship between CC size, NSS, and total lifetime antipsychotic consumption.

Patients with "high" scores at the Sequencing Of Complex Motor Acts subscale showed a smaller CC rostral body, whereas patients with "high" scores at the Integrative Sensory Function subscale showed a smaller CC splenium. For both the NES total and the Sequencing Of Complex Motor Acts subscale, "high" scores were accompanied by an increase of the CC genu. Correlation analyses revealed a significant inverse correlation between the CC rostral body size and the Sequencing Of Complex Motor Acts subscale score. In addition, a significant positive correlation was shown between the CC genu size and both the NES total and the Sequencing Of Complex Motor Acts subscale scores. The presence of NSS and the accompanying CC structural abnormalities were independent on antipsychotic treatment.

Our data provide evidence for an association between NSS and CC morphology and further support the hypothesis of a disturbed interhemispheric functional connectivity in schizophrenia.