The role of cognitive reserve and clinical symptoms in the association between genetic liability for educational attainment and functioning in first-episode psychosis: a mediation analysis

Background: Polygenic risk scores for educational attainment (PRSEA), cognitive reserve (CR), and clinical symptoms are associated with psychosocial functioning in first-episode psychosis (FEP). Nevertheless, the mechanisms underlying their complex interaction is yet to be explored. This study aimed to assess the mediating role of CR and clinical symptoms, both negative (NS) and positive (PS), on the interrelationship between PRSEA and functionality, one year after a FEP. Methods: A total of 162 FEP patients underwent clinical, functional, and genetic assessments. Using genome-wide association study (GWAS) summary results, PRSEA were constructed for each individual. Two mediation models were explored. The parallel mediation model explored the relationship of PRSEA with functionality through CR and clinical symptoms, NS, and PS. The serial mediation model tested a causal chain of the three mediators: CR, NS and PS. Mediation analysis was performed using the PROCESS function V.4.1 in SPSS V.22. Results: A serial mediation model revealed a causal chain for PRSEA > CR > NS > Functionality (β=-0.35, 95%CI [-0.85, -0.04], p