Neurocognitive effects of melatonin treatment in healthy adults and individuals with Alzheimer's disease and insomnia: A systematic review and meta-analysis of randomized controlled trials.
Study Goal
The researchers aimed to determine whether melatonin enhances cognitive function in Alzheimer's disease (AD), insomnia, and healthy subjects.
Results Summary
Melatonin improved MMSE scores in mild-stage AD patients after >12 weeks of treatment but decreased accuracy in healthy subjects during daytime use without affecting reaction time or memory function. Meta-analysis supported melatonin's effectiveness for mild AD and suggested it may be preferable to traditional hypnotics for insomnia.
Population
Alzheimer's disease patients, insomnia patients, and healthy subjects.
Effective Dosage
Not specified
Duration
>12 weeks for AD patients
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
melatonin | increase | mini-mental state examination (MMSE) score | AD patients receiving >12 weeks of melatonin treatment | MD: 1.82 (1.01; 2.63) p < 0.0001 | improved | #1 |
melatonin | increase | MMSE score | mild stage of AD | MD: 1.89 (0.96; 2.82) p < 0.0001 | significantly improved | #2 |
daytime melatonin treatment | decrease | accuracy by correct responses | healthy-subjects | SMD: -0.74 (-1.03; -0.45) p < 0.00001 | notably decreased | #3 |
melatonin | no change | reaction-time score on different stimuli | healthy-subjects | p = 0.37 | did not increased | #4 |
melatonin | no change | memory function | - | p = 0.08 | did not reduce | #5 |
Endogenous melatonin levels are inversely associated with age and cognitive deficits. Although melatonin can improve psychopathological behavior disturbances in clinical trials, whether melatonin may also enhance cognitive function remains elusive. This study examined cognitive outcomes from randomized trials of melatonin treatment for Alzheimer's disease (AD), insomnia, and healthy-subjects. Twenty-two studies met the inclusion criteria (AD = 9, insomnia = 2, healthy-subjects = 11). AD patients receiving >12 weeks of melatonin treatment improved mini-mental state examination (MMSE) score [MD: 1.82 (1.01; 2.63) p < 0.0001]. Importantly, melatonin significantly improved MMSE score in mild stage of AD [MD: 1.89 (0.96; 2.82) p < 0.0001]. In healthy-subjects, although daytime melatonin treatment notably decreased in accuracy by correct responses [SMD: -0.74 (-1.03; -0.45) p < 0.00001], the reaction-time score on different stimuli (p = 0.37) did not increased. Additionally, by pooling of short-term, spatial, and visual memory scores, melatonin did not reduce memory function (p = 0.08). Meta-analysis of MMSE score suggested that melatonin is effective in treatment for mild stage of AD. Additionally, we propose that melatonin may be preferable to traditional hypnotics in management of insomnia.