Meta-Analysis of the Prevalence of Major Depressive Disorder Among Older Adults With Dementia

Objective: Little is known about the overall prevalence of major depressive disorder (MDD) in persons with dementia (ie, "depression in dementia": DpD). The aim of this systematic review and meta-analysis was to determine the prevalence and factors associated with DpD among older adults (age range 58.7-87.8 years). The protocol was registered in the PROSPERO registry (2015:CRD42015020681). Data sources: We searched the following electronic databases: MEDLINE (1946-February 2017), Embase (1980-2017 week 5), and PsycINFO (1967-February 2017) using medical subject headings and free-text search terms for studies in the English language. Study selection: We screened 9,421 studies, and 55 met the inclusion criteria (ie, used validated criteria for both MDD and dementia). Data extraction: Two independent reviewers extracted data from included studies. Meta-analysis was used to determine the pooled estimates and 95% confidence intervals for the prevalence of DpD. Prevalence across dementia subtypes, study setting, diagnostic criteria, and dementia severity was compared in subgroup analyses. Results: The prevalence of MDD in all-cause dementia was 15.9% (95% CI, 12.6%-20.1%). The prevalence of MDD was higher among individuals with vascular dementia (24.7%) compared to Alzheimer's disease (14.8%). Studies using the provisional diagnostic criteria for DpD reported a higher prevalence (35.6%) compared to studies using either the DSM-III-R (13.2%) or DSM-IV (17.3%) criteria. Conclusions: Depression is common among individuals with dementia, and the type of dementia and diagnostic criteria affect prevalence estimates of DpD. Further studies are required to understand factors that lead to the development of DpD and strategies to prevent and treat DpD.