Familial influence of substance use disorder on emotional disorder across three generations.

The concomitant influence of grandparental (Generation 1; G1) and parental (G2) substance use disorder (SUD) on grandchild (G3) emotional disorder (EmD) across three generations is unclear. The present study addressed this in a sample of 284 families participating in the Oregon Adolescent Depression Project. Structured clinical interviews were used to collect psychiatric history data on a community cohort of G2 individuals and their G1 parents. G2 parents rated EmD symptoms in their G3 children (M age=5 years, SD=2.4). Results indicated that G1 SUD was associated with increased risk of G3 EmD symptom elevations, above and beyond the influence of comorbid G1 EmD. G2 SUD was associated with a similar independent increase in risk for G3 EmD symptoms. Also, G1 SUD conferred risk for G2 SUD. Mediational tests indicated that the influence of G1 SUD on G3 EmD was transmitted via its influence on G2 SUD. G1 and G2 SUD did not interact in predicting G3 EmD; rather results suggested an additive influence. There was no evidence that the influence of G1 SUD on G3 EmD was transmitted via G2 EmD. These findings shed light on the multigenerational processes through which SUD influences EmD.