B

In the longitudinal cohort examined, adolescents with both major depression (MD) and alcohol use disorder (AUD) initially showed slightly higher rates of adult depression than those with MD alone; however, once childhood confounders (e.g., abuse, behavior problems, gender) were controlled, this difference disappeared. The authors concluded that MD/AUD comorbidity functions more as a marker of adverse background factors than as an independent cause of poorer depressive outcomes, indicating that comorbidity itself does not lead to worse depression prognosis [Boden & Foulds, 2016, PMID 27643961].