Neurocognitive deficits in first-episode schizophrenic patients and their first-degree relatives

Abstract

Some neuropsychological abilities, particularly those affecting memory, attention and executive function, are impaired amongst both schizophrenic patients and their unaffected relatives, implying that these deficits are at least partly genetic in origin. The objective of this study was to determine whether selected neurocognitive abilities are impaired in first-onset schizophrenic patients and their relatives compared to controls. We examined attention and speed of information processing, memory and learning, verbal function, visuoconstructive abilities and executive function in 207 first-episode schizophrenic patients (163 of whom were drug naive), 322 of their first-degree relatives and 133 unrelated normal controls. The data were subjected to multilevel modelling to compare neurocognitive performance between schizophrenic probands, relatives and controls while taking into account potential correlations among members of the same family; age, gender and years of education were included as covariates. Of the three groups, schizophrenic patients performed poorest on all neuropsychological tests, suggestive of a broad range of neurocognitive deficits. Their first-degree relatives showed a narrower pattern of poor performance on Digit Symbol, Digit Span, Trail Making, Verbal Fluency Test, Tower of Hanoi and WCST-M tests. Our findings show that selected neurocognitive deficits, especially attention and executive function, are impaired in the families of schizophrenic patients. These patterns of neurocognitive deficits may represent endophenotypes +/- denoting varying degrees of vulnerability to schizophrenia. This work was supported by funding from the Chinese National Natural Science Foundation (TL), the Wellcome Trust (TL, DAC, PS), NARSAD (TL), and the Schizophrenia Research fund (TL).