Familial associations in adolescent substance use disorder: a population-based cohort study

Family history of substance use disorder (SUD) affects a child's risk of the disorder through both genetic and shared environmental factors. We aimed to estimate the association between parental or older sibling SUD history with the risk of adolescent SUD diagnosis.

We conducted a population-based cohort study using administrative health-care databases in the Province of Manitoba, Canada, which has a universal and publicly funded health-care system. We included all children born from 1984 to 2000 who have linkages to both parents and were followed until age 18 years. We used generalized estimating equation models to produce unadjusted and adjusted relative risk (RR) estimates of adolescent SUD risk. The study cohort included 134 389 children and 31 307 full sibling pairs; 51.3% were male and 35.4% first-born.

The exposure was SUD diagnosis in a mother or father in either hospitalization or outpatient physician visit records before the children's age of 13 years. The secondary exposure was an adolescent SUD diagnosis in an older full sibling. The outcome was SUD diagnosis during adolescence (13 and 18 years of age) identified in either hospitalization or physician visit records. Children demographics and characteristics associated with SUD diagnosis were included in the models.

Of the 134 389 children, 9.5% had a mother with a history of SUD, 11.3% had a father and 1.3% had an older sibling with a history of SUD diagnosis; 2566 (1.9%) had an adolescent SUD diagnosis. An increased risk of adolescent SUD was observed with SUD history in mothers [adjusted RR (aRR) = 2.50; 95% confidence interval (CI) = 2.26, 2.79], fathers (aRR = 2.15; 95% CI = 1.95, 2.37), both parents (aRR = 3.74; 95% CI = 3.24, 4.31) and older sibling (aRR = 3.85; 95% CI = 2.53, 5.87).

A family history of substance use disorder in parents or older siblings appears to be associated with increased SUD risk in adolescents.