Does Addiction Skip a Generation? Patterns of Intergenerational Transmission of Substance Abuse

Introduction Intergenerational transmission of substance abuse (SA) is established in epidemiological literature. However, the exact patterns are not well understood. The current study explores the association between grandparental SA and grandchild SA as well as the extent to which this association operates via SA (homotypic continuity) and psychopathology (heterotypic continuity) in the parental generation. Methods This prospective multigenerational cohort study (n=29,115) uses data on all individuals born in 1953 and living in the Stockholm Metropolitan Area in 1963 (parental generation), their parents (grandparental generation) and their children (grandchild generation). Linear probability modelling is used to estimate the mediating effect of exposure to parental SA, psychopathology, both, or none, on the association between grandparental SA and grandchild SA. Results Results suggest that grandchildren of individuals with SA are twice as likely to develop SA if their parents have psychiatric disorders and not SA (26% compared to 13% if the grandparents did not have SA), marginally even more likely than those whose parents have SA (25%). Thus, both homotypic and heterotypic intergenerational continuity in SA can be observed. Conclusions This study demonstrates the importance of accounting for alternative pathways of intergenerational transmission of SA and urges addressing the elevated risk of grandchildren of people with SA whose parents have mental health problems.