The Clock and the Brain: Circadian Rhythm and Alzheimer's Disease

Alzheimer's Disease (AD) is the most common type of dementia. The circadian system, which is controlled by the master clock in the Suprachiasmatic Nucleus (SCN) of the hypothalamus, is crucial for various physiological processes. Studies have shown that changes in the circadian rhythms can deteriorate neurodegenerative diseases. Changes in the SCN are associated with cognitive decline in AD. The cognitive impairments in AD, especially memory dysfunctions, may be related to Circadian Rhythm Disturbances (CRDs). Moreover, rhythmic expression of clock genes is disrupted in AD patients. There is a circadian pattern of inflammatory processes in AD, and dysregulation of core clock genes promotes neuroinflammation. The present narrative review addresses the intricate link between CRDs and AD, revisiting the relevant cellular and molecular mechanisms. The association between CRDs and AD highlights the need for further investigation of the underlying mechanisms.