Assortative mating for alcohol use is significant, and couples who report greater discrepancy in alcohol consumption also report greater marital dissatisfaction. Previous research has not investigated how regional and SES differences can shape associations between drinking and spousal support. This study examined the effects of individual drinking (ID), spousal drinking (SD) and regional socioeconomic status (RSES) on individual differences in spousal support. We hypothesized that lower RSES and higher discrepancy between ID and SD predicts less perceived spousal support. Participants were adults from two Australia Twin Registry cohorts. RSES was assessed using postal-code area level Index of Relative Socio-economic Advantage and Disadvantage scores. Linear mixed effect models adjusting for zygosity indicated a three-way interaction between ID, SD, and RSES for women (β = -0.07, p>.05 (-0.11, - -0.03[NG1] ). In other words, discordant drinking effects (e.g., how ID moderated the association between SD) on spousal support were evident in low RSES areas. In contrast, regardless of the discordance between couples, higher levels of SD negatively affected social support in high RSES areas; there was no effect of discordance when SD was high, and a positive effect of discordance when SD was low. Sex-limited biometric genetic twin models were fitted to further explore associations between ID, SD and RSES. Associations between ID and SD were best explained by shared genetic risks for men (rG = 0.88, p<.05). For women, ID-SD associations were best explained by common (rC = 0.77, p<.05) and unique (rE = 0.37, p<.05) environmental risks. For women, associations between ID and RSES were explained by shared genetic risks (rG = 0.93, p<.05), there was no shared risk between ID and RSES for men. The[NG2] association between SD and RSES was explained by shared unique (rE = 0.61, p<.05) and common (rC = 0.49, p<.05) environment risk for men. There was no shared risk between SD and RSES for women. There was a shared genetic risk between SD and spouse support for women (rG = -0.98, p<.05), and a shared common environment association for men (rC = .97, p<.05). The current study indicates how RSES relate to spousal support via its effect on SD and ID. In particular, RSES appears to play a role in how much alcohol discrepancy relates to spouse support. Also for women, similarity in couples’ drinking is more environmentally driven. This suggests that assortative mating related to alcohol use, at least for women, may not play a role in associations between RSES, alcohol use discrepancy and spousal support. However, shared genetic risk does influence how ID, SD, and RSES interactively relate to spousal support in two specific ways, particularly in the shared genetic risk between one’s drinking and regional SES, as well as the risk between how much their partner drinks and how much they perceive their partner’s support.
