Melatonin Benefits The Aging

BUENOS AIRES, Argentina & GUANGZHOU, China--Melatonin normalizes sleep patterns, inhibits cognitive degeneration and protects against age-related macular degeneration (AMD) in elderly individuals, in whom endogenous melatonin production naturally decreases, according to a review authored by researchers from the University of Buenos Aires (Ann N Y Acad Sci, 1057:32736, 2005) and a clinical trial conducted by researchers from Sun Yat-Sen University (Ann N Y Acad Sci, 1057:38492, 2005).

In the review, researchers reported melatonin, a chronobiotic capable of shifting circadian rhythms, benefits the elderly by decreasing sleep latency and increasing sleep efficiency, resulting in increased sleep propensity and synchronization of the circadian clock. They added melatonin is of particular benefit to elderly Alzheimer's disease (AD) patients, in whom melatonin production is severely impaired, by decreasing "sundowning" agitation and reducing variability of sleep onset time. In addition, they noted open and controlled studies have indicated a significant decrease of cognitive deterioration in AD patients treated with melatonin, possibly by promoting slow-wave sleep, augmenting the restorative phases of sleep, and/or protecting neurons against beta-amyloid toxicity. The researchers concluded melatonin provides an innovative neuroprotective strategy to reduce the cost of lifetime treatment of some neuropsychiatric disorders by its combined chronobiotic and cytoprotective properties.

In the clinical trial, researchers tested the theory that supplementing aged people with melatonin may reverse the normal physiological decrease of melatonin, thereby inhibiting oxidative damage in retinal pigment epithelium (RPE) cells, a precursor of AMD, a major cause of severe visual loss in aged people. In this case-control study, 100 patients with dry or wet AMD received 3 mg/d of melatonin for at least three months. Fifty-five patients were followed for more than six months. At the six month mark, visual acuity had been kept generally stable in subjects given melatonin. Further, the researchers noted the change in the fundus (interior eye surface) picture of these patients was "remarkable." Only eight patients showed more retinal bleeding and six had more retinal exudates, while the majority of test subjects given melatonin had reduced pathologic macular changes. The researchers concluded use of 3 mg/d of melatonin seems to protect the retina and to delay macular degeneration.