Meta-analysis of randomized, double-blind, placebo-controlled trials of melatonin in Alzheimer's disease

ObjectiveThis is a meta-analysis of randomized controlled trials (RCTs) of the efficacy of melatonin in Alzheimer's disease (AD). MethodsBoth English (PubMed, PsycINFO, Embase, Cochrane Library databases, and the Cochrane Controlled Trials Register) and Chinese (WanFang Database, Chinese Biomedical Database, and China Journal Net) databases were systematically and independently searched by two authors from their inception until 1 March 2016. Weighted and standard mean differences (SMDs), risk ratio (RR) 95% confidence intervals (CIs) were calculated. In all cases, the random effects model was used. ResultsSeven studies (n=462) with the duration ranging from 10days to 24weeks were identified and analyzed. AD patients receiving melatonin treatment showed prolonged total sleep time at night (n=305; SMD: 0.26, 95% CI: 0.01 to 0.51, I-2=9%, p=0.04). Melatonin did not improve cognitive abilities assessed by the mini-mental state examination and the Alzheimer's Disease Assessment Cognitive Subscale. The discontinuation rate was similar between the melatonin and placebo groups (n=453, RR=0.77, 95% CI: 0.51 to 1.16, I-2=0%, p=0.21). ConclusionMelatonin appears to be effective and safe in improving sleep quality in patients with AD. Copyright (c) 2016 John Wiley & Sons, Ltd.