Sleep and Alzheimer’s Disease

In the normal aging process, sleep changes accompany with increasing sleep fragmentation, nighttime awakenings and greater tendency for daytime sleep. Dementia provokes further deterioration of sleep patterns.1 The prevalence of Alzheimer’s disease (AD), most common form, is rapidly increasing and will probably accelerate dramatically within the next decades as a numbers of people are getting older. Although AD is usually recognized as progressive debilitation of memory, language, and intellect, sleep disturbance is a prevailing and often highly disruptive behavioral symptom associated with AD.2,3 At an early phase of the AD, these neuro behavioral symptoms may appear but seem to be usually associated with a more severe cognitive decline.3,4 The origin of sleep disturbances in AD is considered to be multifactorial. Sleep alterations occur with degeneration of neural pathways that modulate sleep-wake patterns and sleep architecture as well as other environmental factors.3,5 In return, cognitive symptoms may deteriorate through impairment of amyloid-β (Aβ) diurnal pattern and sleep-dependent memory consolidation processes by sleep disorders.6,7 Additionally, a correlation between sleep characteristics and cognitive decline in the elderly has been shown, focusing the fact that sleep and cognition are closely related.8-10 This article will review sleep changes with normal aging and AD, bidirectional relationship between sleep and AD pathology, and underlying mechanism. The result of sleep disturbances in AD will be discussed thereafter. Finally, recommendations as to areas in which future research is needed will be proposed. Received: October 23, 2014 Revised: April 3, 2015 Accepted: April 22, 2015