Numerous observational studies suggest that blood pressure management with antihypertensive drugs may be effective in reducing dementia risk.

To quantify dementia risk in relation to diuretic medication use.

Electronic databases were searched until June 2015. Eligibility criteria: population, adults without dementia at baseline from primary care, community cohort, residential/institutionalized or randomized controlled trial (RCT); exposure, diuretic medication; comparison, no diuretic medication, other or no antihypertensive medication, placebo-control; outcome, incident dementia in accordance with standardized criteria. Adjusted hazard ratios (HR) with 95% confidence intervals (CI) were pooled in fixed-effects models with RevMan 5.3. The overall quality and strength of evidence was rated with GRADE criteria.

Fifteen articles were eligible comprising a pooled sample of 52,599 persons and 3444 incident dementia cases (median age 76.1 years, 40% male) with a median follow-up of 6.1 years. Diuretic use was associated with 17% reduction in dementia risk (HR 0.83; 95% CI 0.75 to 0.90) and a 21% reduction in Alzheimer's disease risk (HR 0.79; 95% CI 0.68 to 0.93). GRADE was rated as moderate. Risk estimates were consistent comparing monotherapy versus combination therapy, study design and follow-up. Meta-regression did not suggest that age, gender, systolic blood pressure, attrition, mortality rate, education, cognitive function, stroke, Apolipoprotein E allele, heart failure or diabetes altered the primary results.

Diuretic medication was associated with a consistent reduction in dementia and Alzheimer's disease risk and the absence of heterogeneity points to the generalizability of these findings.

The authors have not supplied their declaration of competing interest.