Amyloid-β diurnal pattern: possible role of sleep in Alzheimer's disease pathogenesis.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive decline that is a growing public health crisis with a prevalence projected to more than double in the next 20 years. Sleep is frequently impaired in individuals with AD. Further, recent studies have linked numerous age-related sleep disturbances such as poor sleep efficiency and sleep apnea, to future risk of cognitive impairment. Aggregation of amyloid-β (Aβ) into extracellular plaques in the brain is a key step in AD pathogenesis and likely begins 20 years before the onset of dementia. Aβ concentrations in both humans and mouse models show Aβ concentrations rise during wakefulness and fall during sleep, that is, an Aβ diurnal pattern. There is evidence in animal models that changes in sleep time alter Aβ deposition, suggesting that sleep may play a role in AD pathogenesis. A hypothetical model for the role of sleep and the Aβ diurnal pattern in AD pathogenesis is proposed.