Brain activation patterns during visual episodic memory processing among first-degree relatives of schizophrenia subjects

Abstract

Episodic memory deficits are proposed as a potential intermediate phenotype of schizophrenia. We examined deficits in visual episodic memory and associated brain activation differences among early course schizophrenia (n=22), first-degree relatives (n=16) and healthy controls without personal or family history of psychotic disorders (n=28). Study participants underwent functional magnetic resonance imaging on a 3T scanner while performing visual episodic memory encoding and retrieval task. We examined in-scanner behavioral performance evaluating response time and accuracy of performance. Whole-brain BOLD response differences were analyzed using SPM5 correcting for multiple comparisons. There was an incremental increase in response time among the study groups (healthy controls<first-degree relatives<schizophrenia) with no differences in accuracy for encoding. Response time for retrieval was significantly increased in schizophrenia subjects compared to healthy controls with no difference in accuracy. Although there were no significant differences in BOLD responses for the encoding task, we noted increased BOLD response to retrieval in the prefrontal regions (Brodmann areas 9 and 8), thalamus and insula among the schizophrenia subjects compared to healthy controls, and first-degree relatives. Familial risk for schizophrenia may be associated with qualitatively similar but quantitatively milder abnormalities in visual episodic memory retrieval but not for encoding in the prefrontal cortex and thalamus.