Background: It is unclear, whether age-of-onset identifies subgroups of depression.

Aim: To assess the clinical presentation of depression with onset in the early adult age (18-30 years) as compared to depression with later onset (31-70 years).

Method: A total number of 301 patients with first episode depression were systematically recruited. Characteristics including psychiatric co-morbidity, personality disorders and traits, stressful life events prior to onset, family history, and treatment outcome were assessed by structured interviews and compared by chi-square tests for categorical data, t-tests for continuous parametric data and Mann-Whitney U-test for continuous nonparametric data. Logistic and multiple regression analyses were used to adjust the analyses for potentially confounding variables.

Results: Patients with early onset of depression were characterised by a higher prevalence of co-morbid personality disorders, higher levels of neuroticism, and a lower prevalence of stressful life events preceding onset compared to patients with later age-of-onset. There were no differences in severity of the depressive episode, treatment outcome or family loading of psychiatric illness.

Conclusion: Early adult onset of depression is associated with co-morbid personality deviances, whereas late onset is associated with environmental risk factors.