Differential impairment of working memory performance in first-degree relatives of individuals with schizophrenia

Numerous studies have reported neuropsychological impairment in schizophrenia and increasing evidence suggests that individuals with schizophrenia or schizophrenia spectrum disorders and their unaffected first-degree family members exhibit similar deficits in some neuropsychological domains. Substantial modifications to the Wechsler Memory Scale (WMS) have resulted in more sensitive and reliable indicators of various aspects of memory functioning in the WMS-III, which enables generation of auditory, visual and working memory indices.

The aim of the present study was to examine the memory profile of individuals with schizophrenia or schizophrenia spectrum disorder (n = 19), their unaffected first-degree family members (n = 11), and healthy controls (n = 9).

The study involved neuropsychological testing, including the immediate and working memory subtests of the WMS-III, utilizing both auditory and visual domains. Symptom assessment was performed using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN), version 2.0. Two multivariate analyses of covariance (mancova) were conducted: (i) comparing patients, relatives and controls; and (ii) comparing relatives and controls only.

The first analysis indicated that the patient group obtained significantly lower index scores than both relatives and controls on all three indices. The second analysis indicated that the performance of relatives was significantly lower than controls on the working memory index, although there were no significant differences on the auditory and visual immediate index scores.

The differential impairment in working memory performance in clinically asymptomatic family members suggests that the WMS-III working memory index score may be a potential phenotypic marker of schizophrenia.