Neurodevelopmental indices and the development of psychotic symptoms in subjects at high risk of schizophrenia

Background Neurological ‘soft signs’ and minor physical anomalies (MPAs) are reported to be more frequent in patients with schizophrenia than in controls. Aims To determine whether these disturbances are genetically mediated, and whether they are central to the genesis of symptoms or epiphenomena. Method We obtained ratings in 152 individuals who were antipsychotic drug-free and at high risk, some of whom had experienced psychotic symptoms, as well as 30 first-episode patients and 35 healthy subjects. Results MPAs and Neurological Evaluation Scale (NES) ‘sensory integration abnormalities’ were more frequent in high-risk subjects than in healthy controls, but there were no reliable differences between high-risk subjects with and without psychotic symptoms. MPAs were most frequent in high-risk subjects with least genetic liability and NES scores showed no genetic associations. Conclusions The lack of associations with psychotic symptoms and genetic liability to schizophrenia suggests that soft signs and physical anomalies are nonspecific markers of developmental deviance that are not mediated by the gene(s) for schizophrenia.