Neurocognitive performance, psychopathology and social functioning in individuals at high risk for schizophrenia or psychotic bipolar disorder

Introduction: Although cognitive deficits are consistent endophenotypes of schizophrenia and bipolar disorder, findings in psychotic bipolar disorder (BDP) are inconsistent. In this study we compared adult unaffected first degree relatives of schizophrenia and BDP patients on cognition, psychopathology, social functioning and quality of life. Methods: Sixty-six unaffected first-degree relatives of schizophrenia patients (SUnR), 36 unaffected first-degree relatives of BDP patients (BDPUnR) and 102 controls participated in the study. Between-group differences were examined and Discriminant Function Analysis (DFA) predicted group membership. Results: Visual memory, control inhibition, working memory, cognitive flexibility and abstract reasoning were linearly impaired in the relatives' groups. Poorer verbal fluency and processing speed were evident only in the SUnR group. The SUnR group had higher depressive and somatization symptoms while the BDPUnR group had higher anxiety and lower social functioning compared with the controls. Individuals with superior cognition were more likely to be classified as controls; those with higher social functioning, prolonged processing speed and lower anxiety were more likely to be classified as SUnR. Limitations: The relatives' sample is quite heterogeneous; the effects of genetic or environmental risk-factors were not examined. Conclusions: Cognitive functions mediated by a fronto-parietal network, show linear impairments in unaffected relatives of BDP and schizophrenia patients; processing speed and verbal fluency impairments were evident only in schizophrenia relatives. Self-perceived symptomatology and social functioning also differ between schizophrenia and BDP relatives. The continuum seen in patients in several indices was also seen in the cognitive impairments in unaffected relatives of schizophrenia and BDP patients.