Neuropsychological risk indicators for schizophrenia: a review of family studies

We reviewed potential neuropsychological risk indicators for schizophrenia by addressing two broad questions about neuropsychological performance in biological relatives of schizophrenia patients: (1) Is there evidence of deficits, and, if so, (2) are those deficits similar to deficits found in schizophrenia patients themselves? There has not yet been adequate validation of most neuropsychological risk indicators, but promising leads have emerged from studies of relatives of persons with schizophrenia. The strongest evidence of impairment in relatives was in sustained attention, perceptual-motor speed, and concept formation and abstraction; to a slightly lesser extent, mental control/encoding (primarily with distraction) was implicated as well. Impairments in verbal memory and verbal fluency were also found, although these have been less well studied. The pattern of deficits paralleled that found in schizophrenia patients, thus suggesting dysfunction in prefrontal, temporal-limbic, and attentional systems. Findings were similar for children and adult relatives of schizophrenia patients. It is suggested that future studies (1) emphasize comprehensive test batteries, (2) develop composite neuropsychological measures, (3) use profile and deviant-responder analyses, (4) include psychiatric comparison groups, and (5) integrate neuropsychological assessments with brain imaging techniques.