Exposome-Wide Gene-By-Environment Interaction Study of Psychotic Experiences in the UK Biobank

A previous study successfully identified 148 of 23,098 exposures associated with any psychotic experiences (PEs) in the UK Biobank using an exposome-wide association study (XWAS). Furthermore, research has shown that the polygenic risk score for schizophrenia (PRS-SCZ) is associated with PEs. However, the interaction of these exposures with PRS-SCZ remains unknown.

To systematically investigate possible gene-by-environment interactions underlying PEs through data-driven agnostic analyses, we conducted 1) conditional XWAS adjusting for PRS-SCZ to estimate the main effects of the exposures and of PRS-SCZ, 2) exposome-wide interaction study (XWIS) to estimate multiplicative and additive interactions between PRS-SCZ and exposures, and 3) correlation analyses between PRS-SCZ and exposures. The study included 148,502 participants from the UK Biobank.

In the conditional XWAS models, significant effects of PRS-SCZ and 148 exposures on PEs remained statistically significant. In the XWIS model, we found significant multiplicative (multiplicative scale, 1.23; 95% CI, 1.10-1.37; p = 4.0 × 10^-4) and additive (relative excess risk due to interaction, 0.55; 95% CI, 0.32-0.77; synergy index, 0.22; 95% CI, 0.14-0.30; and attributable proportion, 1.59; 95% CI, 1.30-1.91; all ps < .05/148) interactions of PRS-SCZ and the variable serious medical conditions/disability with PEs. We additionally identified 6 additive gene-by-environment interactions for mental distress, help-/treatment-seeking behaviors (3 variables), sadness, and sleep problems. In the correlation test focused on 7 exposures that exhibited significant interactions with PRS-SCZ, nonsignificant or small (r < 0.04) gene-by-environment correlations were observed.

These findings reveal evidence for gene-by-environment interactions underlying PEs and suggest that intertwined pathways of genetic vulnerability and exposures may contribute to psychosis risk.