BACKGROUND Despite considerable interest, there is no consensus regarding the prevalence of depression in later life.

AIMS To assess the prevalence of late-life depression in the community.

METHOD A systematic review of community-based studies of the prevalence of depression in later life (55+). Literature was analysed by level of caseness at which depression was defined and measured.

RESULTS Thirty-four studies eligible for inclusion were found. The reported prevalence rates vary enormously (0.4-35%). Arranged according to level of caseness, major depression is relatively rare among the elderly (weighted average prevalence 1.8%), minor depression is more common (weighted average prevalence 9.8%), while all depressive syndromes deemed clinically relevant yield an average prevalence of 13.5%. There is consistent evidence for higher prevalence rates for women and among older people living under adverse socio-economic circumstances.

CONCLUSIONS Depression is common in later life. Methodological differences between studies preclude firm conclusions about cross-cultural and geographical variation. Improving the comparability of epidemiological research constitutes an important step forward.