Circadian Rhythm Disruption in Aging and Alzheimer’s Disease

Circadian rhythms exhibit many alterations during the normal aging process and more severe disruptions are evident in age-related neurological conditions such as Alzheimer’s disease (AD). Indeed, evidence suggests that circadian rhythm alterations increase susceptibility to AD and conversely that the progressive neuropathological features of AD such as amyloid-beta accumulation further exacerbate circadian rhythm disruption. Impairments in neural function in the master circadian pacemaker in the hypothalamic suprachiasmatic nucleus underlie age- and AD-related alterations in circadian rhythms. Deficits in expression of the clock genes constituting the molecular pathways controlling circadian rhythms also contribute to circadian rhythm impairments and neurodegeneration in senescence(definition) and AD. This chapter describes the mechanisms underlying age- and AD-related alterations in circadian rhythms as well as their possible causes and potential strategies for their amelioration.