Neuropsychological functioning among non-psychotic siblings and parents of schizophrenic patients

Several studies have shown subtle neuropsychological deficits in healthy relatives of schizophrenic patients. However, older relatives and parents have been less frequently assessed than younger adult relatives and siblings. Furthermore, some areas of neuropsychological functioning such as memory and learning have been little studied. Thirty-seven 22-70-year-old non-psychotic parents and siblings of schizophrenic patients were compared to 37 healthy control subjects on a battery of neuropsychological tests (Trail Making, parts A and B, verbal fluency, Wisconsin Card Sorting Test, and four subtests of the Wechsler Memory Scale-Revised: logical memory, design reproduction, verbal paired associates and digit span). Relatives did not differ from control subjects on Wisconsin Card Sorting Test performance and on visual memory, but were significantly impaired on verbal fluency; more subtle deficits were found on Trail Making, part B, digit span and paired associates. A higher proportion of relatives than control subjects showed impairment on verbal fluency and verbal memory. These neuropsychological weaknesseswere present as much in siblings as in parents of schizophrenic patients, and age did not cancel differences between relatives and control subjects. Thus, these subtle deficits seem to be potential phenotypic markers of schizophrenia.