Incidence of late-life depression: a systematic review

In the past years, many studies have examined the prevalence of late-life depression. However, incidence studies, especially those including the oldest age groups, remained rare. The objective of this article is therefore to provide a systematic review on incidence of depressive disorders in latest life.

A systematic search of the literature published between 1985 and 2011 was conducted using MEDLINE, Web of Science, PsycInfo and Cochrane databases. Inclusion criteria were: incidence specified for persons aged≥70 years at baseline, population-based sample or primary care sample. Incidence rates or risks were extracted or calculated.

We found 20 studies reporting incidence according to categorical (n=14) or dimensional diagnoses (n=6). The incidence of depressive disorders varied considerably. Major Depression (MD) was found to occur less often than Minor Depression (MinD), whereas clinically relevant depressive symptoms are at least as frequent as MinD. The incidence rate of MD was 0.2-14.1/100 person-years, and incidence of clinically relevant depressive symptoms was 6.8/100 person-years. Female incidence was mostly higher than male. Associations between age and incidence revealed to be rather inconsistent between studies.

Methodological diversity of the studies concerning diagnostics, data collection methods, incidence definitions and sampling make the results difficult to interprete.

This review is the first to have focused on incidence studies on depression in latest life. The frequent occurrence of clinically relevant depressive symptoms will have to be considered in future health care planning. Physical health and psychosocial influences appear to be key variables in depression prevention.