Prevalence of minor depression in elderly persons with and without mild cognitive impairment: a systematic review.

BACKGROUND: Minor depression (MinD) and mild cognitive impairment (MCI) are common disorders in late life that often coexist. The aim of the present review is to demonstrate prevalence rates of minor depression in older patients with and without MCI. METHODS: Electronic database searches were performed through Medline, ISI Web of Knowledge, Psycinfo, and Cochrane library. Two independent reviewers extracted the original studies based on inclusion criteria: representative study population aged 55 and older, diagnostics of MinD according to DSM. Data on prevalence rates, risk factors, comorbidity and health care usage were analyzed. RESULTS: Point prevalence for MinD is higher in medical settings (median 14.4%) than in the community-based settings (median 10.4%) and primary care patients (median 7.7%). Although minor depression is rarely investigated in elderly persons with MCI, nearly 20% of patients with MCI seem to suffer from MinD. No data was found on the prevalence of MCI in patients with MinD. Risk factors associated with MinD include female gender, history of cerebrovascular diseases, generalized anxiety disorder, loneliness, and long-term institutional care. LIMITATIONS: Methodological differences of included studies resulted in a broad range of prevalence rates. No data is shown regarding the prevalence of MCI in MinD group due to insufficient evidence. CONCLUSIONS: Our review indicates that MinD is frequent in elderly population. MCI among those subjects has not been sufficiently investigated. Future studies based on clinical structured interviews should be performed in longitudinal design in order to differentiate late-life depression from progressive MCI or early manifestation of Alzheimer's disease.