The Dose- and Duration-Dependent Association between Melatonin Treatment and Overall Cognition in Alzheimer's Dementia: A Network Meta-Analysis of Randomized Placebo-Controlled Trials.

BACKGROUND: While Alzheimer's dementia (AD) has a prevalence as high as 3-32% and is associated with cognitive dysfunction and the risk of institutionalization, no efficacious and acceptable treatments can modify the course of cognitive decline in AD. Potential benefits of exogenous melatonin on cognition have been divergent across trials.

OBJECTIVE: The current network meta-analysis (NMA) was conducted under frequentist model to evaluate the potential benefits of exogenous melatonin supplementation on overall cognitive function in participants with AD in comparison with other FDA-approved medications (donepezil, galantamine, rivastigmine, memantine, and Namzaric).

METHODS: The primary outcome was the changes of the cognitive function [measured by mini-mental state examination (MMSE)] after treatment in patients with Alzheimer's dementia. The secondary outcomes were change in the quality of life, behavioral disturbance, and acceptability (i.e. drop-out due to any reason and rate of any adverse event reported).

RESULTS: The current NMA of 50 randomized placebo-controlled trials (RCTs) revealed that the medium-term low-dose melatonin was associated with the highest post-treatment MMSE (mean difference = 1.48 in MMSE score, 95% confidence intervals [95% CIs] = 0.51 to 2.46) and quality of life (standardized mean difference = -0.64, 95% CIs = -1.13 to -0.15) among all of the investigated medications in the participants with AD. Finally, all of the investigated exogenous melatonin supplements were associated with similar acceptability as was the placebo.

CONCLUSIONS: The current NMA provides evidence for the potential benefits of exogenous melatonin supplementation, especially medium-term low-dose melatonin, in participants with AD.

TRIAL REGISTRATION: The current study complies with the Institutional Review Board of the Tri-Service General Hospital (TSGHIRB: B-109-29) and had been registered in PROSPERO (CRD42020193088).