Alcohol misuse and relationship breakdown: findings from a longitudinal birth cohort.

BACKGROUND This study examined the associations between measures of alcohol abuse/dependence (AAD) and relationship dissolution from ages 19 to 30 in a New Zealand birth cohort. METHODS The outcome measure was self-reported breakdown of a marital/cohabiting relationship during each year from age 20-21 to age 29-30. The study also used contemporaneous and one-year lagged measures of AAD symptoms; and time-dynamic covariate factors including life stress, other substance use, mental health status, peer and partner substance use and offending, unemployment, exposure to intimate partner violence, and prior relationship breakdown. Data were analysed using conditional fixed effects regression modelling augmented by time-dynamic covariate factors to control for confounding. RESULTS Those with three or more AAD symptoms had unadjusted odds of relationship breakdown that were 2.17-2.23 times higher than those with no symptoms, but these associations did not differ by gender. Adjustment of the associations for both unobserved fixed effects and time-dynamic covariate factors reduced the magnitude of the associations, with those with three or more AAD symptoms having rates of relationship breakdown that were 1.57-1.66 times higher than those with no symptoms. CONCLUSIONS The results suggest a causal association between alcohol misuse and relationship breakdown, with estimates suggesting that alcohol use disorder accounted for 4.5-4.6% of marital/cohabiting relationship dissolution in the cohort.