PURPOSE: The aim of the present study was to contribute to the inconsistent literature on the comorbid relationship of alcohol problems and depressive symptoms from late adolescent to emerging adulthood by accounting for their trajectories and their conjoint relationship while controlling for the influence of externalising symptoms.

METHODS: We utilised data, from a longitudinal school cohort from Northern Ireland (Belfast Youth Developmental Study), over three time points where the participants were 16, 17 and 21 years of age. A total of 3118 participants were included, 1713 females and 1405 males. Second-order latent growth models were applied to examine growth trajectories. Parallel process growth models were used to assess whether growth trajectories of the symptoms were associated. Externalising symptoms were subsequently added as a covariate.

RESULTS: Alcohol problems among males significantly increased over time but decreased in females. Depressive symptoms initially increased then decreased in both genders. Results indicated associations of the alcohol problems and depression, both initially and with time. Accounting for externalising symptoms only somewhat diminished this effect in males but not in females. An increase of initial levels of depression was associated with a decrease in alcohol problems over time. This association was only true among females. After controlling for externalising symptoms, the relationship was no longer observed.

CONCLUSIONS: The present study provides further evidence of a significant relationship of alcohol problems and depression in adolescents and further supports a small literature indicating that depression may have protective effects of alcohol problems. Finally, the study shows the importance of accounting for externalising symptoms.