Background: Neurological abnormalities (NAs) are well recognized in schizophrenia, though their genetic and environmental determinants, and pathophysiological significance, are poorly understood.
Methods: Sixty-three twin pairs, varying in their zygosity and concordance for schizophrenia, and 73 unaffected control twin pairs were examined for total, primary and integrative NAs using the Neurological Evaluation Scale.
Results: NAs were increased in probands with schizophrenia compared to nonschizophrenic co-twins and to healthy control twins but there were no significant differences between patients from the concordant and discordant pairs. NAs in the nonpsychotic co-twins from discordant pairs were increased compared to control twins. There were no significant differences in NAs between the nonschizophrenic co-twins from monozygotic (MZ) and dizygotic (DZ) discordant pairs, but the within pair correlations were greater in the MZ compared to DZ pairs. NAs were modified in all groups by pre-morbid schizotypal traits, and in patients by anti-psychotic medication.
Conclusions: NAs in schizophrenia are determined in part by genetic risk for the illness but the presence of premorbid schizotypal traits, and anti-psychotic medication confer additional risk for NAs.