T41. SEX DIFFERENCES IN VERBAL MEMORY IN FIRST-EPISODE PSYCHOSIS AND HEALTHY CONTROLS

Verbal memory (VM) is one of the most affected cognitive domains in patients with schizophrenia and a robust predictor of functional outcome. There are well-documented sex differences in verbal memory in healthy individuals, which may be particularly pertinent to study in psychosis. For instance, in healthy individuals, women tend to have significantly better verbal memory performance relative to men. Given that male psychosis patients present with an earlier age of onset, more negative symptoms, and have poorer functional outcomes than women, consideration of sex differences may lead to a better understanding of VM impairment in psychosis and its wide-ranging effects on outcome. Studies of first-degree relatives of schizophrenia patients and those at clinical high-risk for psychosis demonstrate specific impairments in immediate but not delayed recall, suggesting that impaired immediate recall may be a marker for psychosis. Our aims were thus (1) to investigate sex differences in VM ability in first-episode psychosis (FEP) patients and controls, and (2) to distinguish between sub-domains of memory impairment in FEP in relation to sex differences, by examining both immediate and delayed recall performance. 437 FEP patients (301 males, 136 females; age range 14–35) and 138 (96 males, 42 females matched on age, sex, handedness, and socioeconomic status) were included. VM was calculated from the Logical Memory Subscales of the Wechsler Memory Scale (n=324) or a computerized VM task from the CogState Research Battery (n=251). Performance of the matched control group was used as normative data to derive z-scores for VM, as well as for immediate and delayed recall separately. Main effects of sex (males, females) and diagnostic group (patients, controls), as well as group × sex interactions, on VM were examined, covarying for battery version. No significant group × sex interactions were found with respect to memory performance, F(1,570)=0.64, p=0.43. Significant main effects of group and sex on VM were observed, where FEP patients performed worse than controls, F(1,570)=75.69, p<.001, and males performed worse than females, F(1,570)=31.70, p<.001. Analyzing VM subdomains separately, no significant group × sex interactions were found for either immediate or delayed recall. However, the same pattern of results emerged in terms of main effects, with patients performing worse than controls on both immediate, F(1,570)=85.37, p<.001, and delayed recall, F(1,570)=65.33, p<.001, and males performing worse than females on both immediate, F(1,570)=31.15, p<.001, and delayed recall, F(1,570)=34.55, p<.001. In accordance with past studies, we demonstrated that patients with FEP were more impaired than controls in VM, and that males performed worse than females. The lack of significant group × sex interactions suggests there is no additive effect of male sex and patient status that contributes to VM performance, highlighting the opportunity to characterize individual differences in memory ability that can be observed in healthy people to better delineate the nature of these deficits in schizophrenia. Further, the null effect of differences between immediate and delayed recall indicates that the impairments extend to both subdomains of VM in both FEP patients and healthy individuals. Without explicitly studying sex differences in schizophrenia, implementation of otherwise well-informed treatment strategies may inadvertently ignore meaningful differences in the presentation and course of psychosis between males and females, and ultimately hinder the development of more effective interventions. Future studies should examine whether sex differences in memory are also apparent in enduring psychosis.

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