Abstract

Context:The close association between generalized anxiety disorder (GAD) and major depressive disorder (MDD) prompts questions about how to characterize this association in future diagnostic systems.Most information about GAD-MDD comorbidity comes from patient samples and retrospective surveys.Objective: To revisit the sequential and cumulative comorbidity between GAD and MDD using data from a prospective longitudinal cohort.Design: Prospective longitudinal cohort study.Setting: New Zealand.Participants: The representative 1972-1973 Dunedin birth cohort of 1037 members was followed up to age 32 years with 96% retention. Main Outcome Measures:Research diagnoses of anxiety and depression were made at ages 11, 13, 15, 18, 21, 26, and 32 years.Mental health services were reported on a life history calendar.Results: Sequentially, anxiety began before or concurrently in 37% of depression cases, but depression began before or concurrently in 32% of anxiety cases.Cumulatively, 72% of lifetime anxiety cases had a history of de-