Neuropsychological indicators of the vulnerability to schizophrenia.
Schizophrenia is associated with enduring deficits in neuropsychological functioning. It is widely undecided if the various aspects of neuropsychological impairment are a consequence of the disorder or if they are also present premorbidly and in populations at increased risk for schizophrenia (vulnerability markers). Neuropsychological deficits in healthy relatives of schizophrenic patients who are at an elevated risk for schizophrenia and who did not yet pass the period of risk would indicate that these deficits are vulnerability markers. This hypothesis was tested for three neuropsychological paradigms which have been proven to distinguish schizophrenic patients from controls. 33 siblings of drug-free schizophrenic probands revealed deficits has compared to 33 matched healthy controls in a blurred single target version of the Continuous Performance Test and in a multiple item version of the Span of Apprehension Test but not so in less difficult versions of both tests or in the time needed to react to stimuli with shifting modality.