clearly the direction of effect and rule out explanations other than G × E. For example, those with high genetic propensity for alcohol misuse who experience low alcohol misuse may be more likely to enter a romantic relationship than those with higher levels of misuse. Thirdly, our measure of romantic partnerships did not include relationship characteristics. We examined romantic partnerships status as the moderator of polygenic scores, given the well-established link between relationship status and health in the literature [23]. However, research also suggests that the association between romantic relationship and alcohol use is complex and depends, in part, on relationship characteristics (e.g. relationship quality, partner’s drinking, emotional support) [62]. Identifying data sources that contain phenotypical information on both the respondent and their partner will be important for future research understanding G × E mechanisms. Finally, our measure of AD symptoms was a life-time measure. Supplemental analyses revealed similar patterns between life-time and past 12-month symptoms (see Supporting information, Fig. S3 and Table S7).
