Protective Roles of Melatonin in Alzheimer s Disease: A Review of Experimental and Clinical Research

Alzheimer s disease (AD) stands as the most prevalent neurodegenerative disorder, marked by neuronal loss, synaptic dysfunction, atrophy in various brain regions, cognitive decline, dementia, the production of β-amyloid (Aβ) peptide, and the presence of neurofibrillary tangles. Melatonin, also known as N-acetyl 5-methoxy tryptamine, is a hormone regulated by circadian rhythms and plays a crucial role in certain neurodegenerative conditions, including AD. In individuals with AD, alterations have been observed in the pineal gland hormone melatonin (MLT), the activity of enzymes associated with MLT synthesis, and the density of MT1 receptors in the suprachiasmatic nucleus (SCN) of the hypothalamus. The growing body of literature indicates a rising interest in utilizing MLT for AD intervention. Melatonin has shown several potential benefits in AD, such as mitigating mitochondrial dysfunction, reducing Aβ toxicity, scavenging free radicals, and even ameliorating circadian dysregulation, which includes addressing issues like sundowning and sleep disturbances. Recent studies suggest that MLT might serve as a potential biomarker for assessing the severity and progression of AD. This paper aimed to provide an overview of recent research on three key aspects: (1) MLT physiology, (2) the role of MLT in the learning and memory processes, and (3) an exploration of studies investigating the role of MLT in AD.