Melatonin is a hormone produced primarily by the pineal gland in the brain and its main function is to regulate the sleep-wake cycle, which is also known as the circadian rhythm. Therefore, melatonin supplements may help people who have difficulty falling and staying asleep. A new study has found that melatonin supplementation is associated with a reduced risk of developing age-related macular degeneration (AMD) and may also slow the progression of this disease, suggesting its potential as a preventative therapy.
Macular degeneration is the most common cause of blindness in people over 65 years of age and is caused by damage to blood vessels, or the growth of new blood vessels in or around the macula – which is located in the centre of the retina – and is characterised by a progressive decrease in visual acuity. Melatonin has been shown to counteract several processes known to be involved in age-related macular degeneration (AMD). However, it is not yet clear whether it can actually offer benefits against AMD.
To find out, researchers from Case Western Reserve University School of Medicine and Cole Eye Institute conducted a study whose results have been published in JAMA Opthalmology and reveal that melatonin use was associated with a decreased risk of developing and progressing AMD. Although lifestyle factors may have influenced this association, these findings provide a basis for further investigation into the efficacy of melatonin as a preventative therapy for AMD.
An aid to prevent the development of AMD or its progression
The researchers used data from TriNetX, a national database of inpatient and outpatient electronic medical records in the US, collected between December 4, 2023, and March 19, 2024. They included patients aged 50 years or older, 60 years or older, and 70 years or older with no history of AMD and with a history of nonexudative AMD. They searched for melatonin-related drug codes between November 14, 2008, and November 14, 2023. Patients were then categorized into either a melatonin group or a control group based on the presence of these codes.
Researchers found that melatonin was linked to a lower risk of age-related visual decline in individuals who had not previously experienced visual decline. In addition, melatonin was found to be linked to a lower risk of worsening vision in people who were already experiencing vision loss at an early stage.
Age-related macular degeneration is the leading cause of visual impairment in Europe, affecting around 67 million people in the EU, according to a 2019 study. Furthermore, due to the progressive ageing of the population and the fact that AMD mainly affects adults over 50 years of age, the number of people affected is expected to increase by 15% by 2050.
Melatonin may be a potent antioxidant and anti-inflammatory agent, properties that could counteract the processes that cause AMD.
“In this cohort study of 121,523 patients with no history of AMD aged ≥50 years, melatonin intake was associated with a lower risk of developing AMD,” the study authors wrote. “Similarly, among 66,253 patients with preexisting nonexudative AMD, melatonin supplementation was negatively associated with the rate of progression to exudative AMD,” they added.
The authors point out that animal and human studies have shown that melatonin can be a potent antioxidant and anti-inflammatory agent and have both antiangiogenic properties (which prevent the formation of new blood vessels) and mitochondrial preservation properties (the health of mitochondria is key to maintaining the proper functioning of cells), and that these properties could counteract the processes that cause AMD.
The new findings “provide a rationale for expanding clinical research into the potential therapeutic efficacy of melatonin in preventing the development of AMD or its progression,” they say. They also acknowledge, however, that further research is needed to validate these results, as other factors such as smoking or access to medical care may also influence the disease.
