Relation between age of first drinking and mental health and alcohol and drug disorders in adulthood: evidence from a 35-year cohort study.

Abstract

To estimate associations between age of first drinking (AFD) and alcohol use disorder, nicotine dependence, cannabis dependence, illicit drug dependence, major depression and anxiety disorder in adulthood, net of a series of covariate factors. Data were obtained from a longitudinal birth cohort. Christchurch, New Zealand. The Christchurch Health Development Study (CHDS), a longitudinal study of a cohort born in 1977 and studied to age 35years. Analysis samples ranged in size from 1056 (ages 11-13years) to 962 (age 35years); 50.2% of the total sample was male. A measure of AFD (ages 5-13+ years) was generated using latent class analysis. Outcome measures included: major depression, anxiety disorders, alcohol use disorder, nicotine dependence, cannabis dependence and other illicit drug dependence during the period 15-35 years. Covariate factors measured during childhood included family socio-economic status, family functioning, parental alcohol-related attitudes/behaviours and individual factors. Earlier AFD was associated significantly (P<0.05) with increased risk of later alcohol use disorders, nicotine dependence and illicit drug dependence, and was associated marginally (P<0.10) with cannabis dependence, but not depression or anxiety disorder. After controlling for covariate factors, the associations between AFD and outcomes were no longer statistically significant [alcohol use disorder: B=-0.07, 95% confidence interval (CI)=-0.22, 0.08; nicotine dependence: B=-0.15, 95% CI=-0.34, 0.04; illicit drug dependence: B=-0.29, 95% CI=-0.73, 0.15; cannabis dependence: B=-0.05, 95% CI=-0.31, 0.22]. The associations between age of first drinking and later alcohol/drug disorders appear to be accounted for at least to some degree by factors related to characteristics of the individual and family during childhood.