Alzheimer’s Disease and Dementia Linked to Poor Sleep
New research has found that lack of sleep increases the risk of Alzheimer’s disease, increases the risk of dying from the disease, and increases the risk of dementia.
Researchers from Johns Hopkins School of Public Health studied 70 elderly adults with an average age of 76 years old. They conducted examinations on each, which included positron emission tomography on their brains to determine their “beta-ameloid burden.”
Other research has linked a greater build up of beta-amyloid plaque to the incidence of Alzheimer’s disease. This and tau protein fibers tangles within the brain are both recognized as key characteristics of Alzheimer’s disease.
The positron emission tomography allowed the researchers to observe these symptoms in the patients. Before this technique, the beta-amyloid protein load and neuron tangles could only be seen during autopsy.
In addition to this analysis, the researchers also conducted questionnaires to determine the sleep habits of the elderly subjects.
They found that greater beta-amyloid deposits were linked with lower sleep quality and greater sleep disturbances. They concluded:
“Among community-dwelling older adults, reports of shorter sleep duration and poorer sleep quality are associated with greater beta-amyloid burden.”
Another recent study also found this same connection. Here University of Toronto medical researchers followed 698 elderly adults without dementia were followed for six years. Their average age was 82 years old, and 77% were women. The subjects were examined yearly and their sleep habits were recorded.
In this study, beta-amyloid burden and neurofibrillary tangles were identified only among the 201 patients who died during the six years.
The researchers found that among those 201 people who died, 98 of them had developed Alzheimer’s disease.
The researchers compared the dead subjects’ records of sleep quality with the incidence of Alzheimer’s disease. They found that better sleep reduced the incidence of Alzheimer’s disease by 33%.
They also specifically linked better sleep with the ε4 gene allele neurofibrillary tangle interaction. Here better sleep reduced the interaction – connected with beta-amyloid buildup – by 42%.
A study on dementia with Lewy bodies confirms the importance of sleep and its effect on dementia. In this study, Mayo Clinic researchers studied 75 patients with dementia with Lewy bodies together with their sleep histories. They found that 35 of the patients had probable REM sleep behavior disorder.
The existence of Lewy bodies among the brain is also prevalent in Alzheimer’s disease. While the mechanisms of the Lewy bodies are still not well understood, they almost always occur with beta-amyloid plaque build up and neurofibrill tangles.
The researchers graded the patients using MRIs to estimate their beta-amyloid deposit and neuron tangles burden. Among those with “high-likelihood” dementia – more beta-amyloid and tangles – 60% had REM sleep problems. Among those with “low-likelihood” dementia – only 6% had REM sleep behavior disorder.
They concluded that REM sleep difficulties were related to greater risk of dementia.
Other research has found that sleeping helps brain cells clear toxins, along with consolidate memories. Much of this takes place in REM (rapid eye movement) sleep.
Lim AS, Yu L, Kowgier M, Schneider JA, Buchman AS, Bennett DA. Modification of the Relationship of the Apolipoprotein E ε4 Allele to the Risk of Alzheimer Disease and Neurofibrillary Tangle Density by Sleep. JAMA Neurol. 2013 Oct 21. doi: 10.1001/jamaneurol.2013.4215.
Spira AP, Gamaldo AA, An Y, Wu MN, Simonsick EM, Bilgel M, Zhou Y, Wong DF, Ferrucci L, Resnick SM. Self-reported Sleep and β-Amyloid Deposition in Community-Dwelling Older Adults. JAMA Neurol. 2013 Oct 21. doi:10.1001/jamaneurol.2013.4258.
Murray ME, Ferman TJ, Boeve BF, Przybelski SA, Lesnick TG, Liesinger AM, Senjem ML, Gunter JL, Preboske GM, Lowe VJ, Vemuri P, Dugger BN, Knopman DS, Smith GE, Parisi JE, Silber MH, Graff-Radford NR, Petersen RC, Jack CR Jr, Dickson DW, Kantarci K. MRI and pathology of REM sleep behavior disorder in dementia with Lewy bodies. Neurology. 2013 Oct 9.
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