Gender differences in subtypes of depression by first incidence and age of onset: a follow-up of the Lundby population.

The Lundby Study is a prospective mental health survey in a community population (N = 3563), in which data were collected in 4 waves of field-work between 1947 and 1997. We investigated gender differences during the follow-up in overall first incidence rates, ages of onset, and incidence by age of onset patterns, in different subtypes of depression. The overall incidence rate in females was higher than males for most subtypes of depression. However, for depression with melancholic and/or psychotic features, the overall first incidence rate did not differ significantly between the genders. The mean age of onset did not differ significantly between females and males in any of the depressive subtypes. Nevertheless, females and males had different first incidence rates by age of onset patterns for unipolar non-melancholic DSM-IV mood disorder and major depressive disorder (MDD), with a consistent gender incidence gap across all ages, but with the most conspicuous gender gap in middle age. The first incidence rates by age of onset patterns for DSM-IV MDD with melancholic and/or psychotic features did not differ significantly between the genders. The findings support that females are more prone than males to develop depression with medium severity, but no gender differences were found in melancholic and/or psychotic depression. The findings may support that unipolar non-melancholic depression and melancholic and/or psychotic depression represents different disorders. Tentative explanations for this are discussed.