Neurocognitive functioning and schizophrenia spectrum disorders can be independent expressions of familial liability for schizophrenia in community control children: the UCLA family study

Abstract

This study provided a further test of the hypothesis that certain neuromotor, language and verbal memory dysfunctions reflect genetic predisposition to schizophrenia, by examining the effects of family loading for schizophrenia (FLS) in normal controls without personal histories of schizophrenia or attention deficit hyperactivity disorder. In a case control design, 11 community controls (CC) with FLS were compared to 47 CC without FLS on tests of expressive and receptive language, visual motor coordination, full scale intelligence and verbal memory. In this study, FLS primarily reflects the incidence of schizophrenia spectrum diagnoses in the second-degree relatives of CC probands. CC probands with FLS had significantly poorer general intelligence, expressive and receptive vocabulary abilities, visual motor coordination and slower motor speed than CC probands without FLS. The variance in neurocognitive functioning associated with FLS is not due to the presence of any psychiatric disorders in CC probands, nor the presence of schizophrenia spectrum disorders in their parents. The relation between FLS and neurocognitive and neuromotor functioning in CC probands was moderated by the parent's cognitive functioning. The results of the present study indicate that familial liability to schizophrenia can be transmitted across two generations, independent of the presence of schizophrenia spectrum disorders in either the parent or proband, and account for significant variance in proband neurocognitive and neuromotor functioning. These findings suggest the neurocognitive and neuromotor functioning and schizophrenia spectrum disorders can be relatively independent expressions of familial liability to schizophrenia.