Despite the increasing interest and social impact of mood disorders in elderly, there is no consensus regarding the frequency of depression in later life (LLD). A lack of epidemiological data mainly concerns the depression that occurs at age≥ 65 years, named Late Onset Depression (LOD).

To provide current estimates of the prevalence of LLD and LOD in elderly of the population-based GreatAge Study and to determine the prevalence of untreatment in both positive groups.

A cross-sectional analysis of the 500 participants (60% males) of the population-based GreatAge Study, aged≥ 65 years, was performed. Depression diagnosis was assessed through the SCID and categorized as major and minor depression (dysthymia, adjustment disorders and depression nos). The antidepressant's use was obtained from a standardized anamnestic interview.

The prevalence of positive population for any DSM-VI disorder amounted to 22% (29% females; 17,3% males). The prevalence of LLD was estimated to be 10% (14,5% of women; 7% of men) distinct as major (5,4%) and minor (4,6%) depression. The prevalence of LOD was estimated to be 5,2%. No differences for gender were recorded (p=0.694). In the whole sample major and minor LOD are equally distributed (2,6%). The prevalence of treated subjects amounts to 40% for LLD and 46,2% for LOD (p=0.355).

Population-based studies have been useful in defining clinical characteristics and prognostic indicators of LOD. Our frequency rates are generally comparable with the range identified by previous studies conducted in other Western countries. Exceptions are represented by subtypes and gender frequency.