Soft neurological signs in schizophrenic patients and their nonpsychotic siblings.

This study examined neurological signs as familial vulnerability factors to schizophrenia. Fifteen Chinese schizophrenic patients, 21 of their nonpsychotic siblings, and 26 healthy volunteers, matched for age, sex, and education, were assessed by using the Cambridge Neurological Inventory. Results showed that patients and their siblings had significantly higher global neurological impairment than controls. The severity of motor coordination impairment of the siblings was in between patients and controls. This may suggest either patients have higher genetic vulnerability for the neurological abnormality and schizophrenia than their nonpsychotic siblings or the disease can further worsen the preexisting neurological deficit. Disinhibition signs were similar in patients and siblings, but significantly less in controls indicating its familial nature. Extrapyramidal and sensory integration signs were similar in siblings and controls, but significantly more severe in patients, suggesting nonfamilial abnormalities. In conclusion, these findings may imply different etiological origins for different subgroups of neurological signs.