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

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. However neuropsychological performance can be altered by medication, and has rarely been examined in first onset, drug naive patients. 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 naïve), 322 of their first-degree relatives and 133 unrelated normal controls. The data were subjected to multilevel modeling 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 at all neuropsychological tests, suggestive of a broad range of neurocognitive deficits. Their first-degree relatives showed a narrower pattern of poor performance at 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 and may be of value in future molecular genetic studies.