Intergenerational transmission of alcohol misuse: mediation and interaction by school performance in a Swedish birth cohort.

BACKGROUND: Children whose parents misuse alcohol have increased risks of own alcohol misuse in adulthood. Though most attain lower school marks, some still perform well in school, which could be an indicator of resilience with protective potential against negative health outcomes. Accordingly, the aim of this study was to examine the processes of mediation and interaction by school performance regarding the intergenerational transmission of alcohol misuse.
METHODS: Data were drawn from a prospective Swedish cohort study of children born in 1953 (n=14 608). Associations between parental alcohol misuse (ages 0-19) and participants' own alcohol misuse in adulthood (ages 20-63) were examined by means of Cox regression analysis. Four-way decomposition was used to explore mediation and interaction by school performance in grade 6 (age 13), grade 9 (age 16) and grade 12 (age 19).
RESULTS: Mediation and/or interaction by school performance accounted for a substantial proportion of the association between parental alcohol misuse and own alcohol misuse in adulthood (58% for performance in grade 6, 27% for grade 9 and 30% for grade 12). Moreover, interaction effects appeared to be more important for the outcome than mediation.
CONCLUSION: Above-average school performance among children whose parents misused alcohol seems to reflect processes of resilience with the potential to break the intergenerational transmission of alcohol misuse. Four-way decomposition offers a viable approach to disentangle processes of interaction from mediation, representing a promising avenue for future longitudinal research. © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ.