Some of the relatives of people with schizophrenia show impairments of memory and executive function. It is not known, however, whether within these domains there is a class of processes that is especially impaired. Seventy schizophrenic or schizoaffective patients, 115 of their relatives and 66 normal controls underwent a series of assessments evaluating modality specific recall/learning, and aspects of executive functioning, including, planning ability, spatial working memory, strategy formation and rapid mental flexibility. The pattern of performance across cognitive processes was assessed using z-scores that allow direct comparison between tests with different raw score metrics. Selectivity of deficit was evaluated by subtracting the z-score of each cognitive process from the mean of the z-scores of those remaining. Patients performed out worse than controls on most measures, with verbal immediate recall and visual memory/learning the most impaired. Their relatives showed lower scores than controls on verbal and visual memory/learning and strategy formation; verbal memory and strategy formation remained impaired after eliminating those relatives with a psychiatric diagnosis. Consistent with the findings in their schizophrenic kin, healthy relatives also showed disproportionate impairments in verbal immediate recall. Our finding of a selective deficit in verbal memory among relatives suggests that such impairment constitutes a familial, probably genetic, risk factor for schizophrenia.
Copyright 2003 Wiley-Liss, Inc.