To test the interaction of SIMD and PGRS with cognitive measures as the dependent variable, age, sex, alcohol consumption, PGRS and SIMD were included as main effects and the interaction term ‘polygenic risk score*SIMD’. To control for confounders, each covariate was entered as an interaction with the genetic (PGRS) and environmental (SIMD) effect as recommended elsewhere (Keller 2013). The P‐values presented are raw P‐values uncorrected for multiple testing. False discovery rate (FDR) was implemented in the R package ‘fdrtools’ to estimate the local FDR.
