Poor Sleep May Increase Alzheimer’s Risk

Chronic sleep deprivation and sleep disorders are associated with many health problems including cardiovascular diseases, diabetes, obesity, anxiety, and depression [1]. A study published this month in Neurology adds Alzheimer's disease to that list [2].

The study investigated the relationship between sleep quality and Alzheimer's by measuring markers of the disease in spinal fluid. The participants—101 "cognitively normal" people with an average age of 63 and either a family history or genetic risk factor for Alzheimer's—completed a survey on sleep quality and provided spinal fluid samples. Researchers discovered that worse sleep quality, more sleep problems, and daytime sleepiness were associated with altered levels of markers for beta-amyloid?, tau?, and inflammation in the spinal fluid, all of which are involved in Alzheimer's. These associations persisted even after controlling for factors such as race, BMI, education, symptoms of depression, or use of sleep medications.

It is possible that sleep problems promote the development of Alzheimer's, or that the changes Alzheimer's produces in the brain reduces sleep quality, or both, which may create a vicious cycle. For example, a previous study in older adults has shown that beta-amyloid proteins in the brain (which make up Alzheimer's plaques) may interfere with sleep quality and memory formation [3]. And preclinical studies suggest that sleep disturbance can promote the formation of beta-amyloid plaques and reduce the removal of beta-amyloid from the brain. Toxic proteins including beta-amyloid and tau that can eventually form plaques and tangles are "flushed out" of the brain during sleep, so it makes sense that poor sleep would result in higher levels [4]. A recent study in middle-aged adults reported that disrupting just one night of sleep during the deep non-REM phase is enough to cause a change in spinal fluid levels of beta-amyloid [5].

Though we still have unanswered questions about the role of poor sleep in the development of Alzheimer's, there is already a clinical trial testing the potential of sleep aids to treat Alzheimer's disease [6].

If you don't get enough sleep or have poor quality sleep, addressing these issues may help lower your risk for Alzheimer's disease. Establish a bedtime routine and maintain a regular sleep schedule. If you suspect you have insomnia or sleep apnea, talk to your healthcare provider about treatment options. (Not all medications improve deep non-REM sleep, and some carry brain health risks.) The Centers for Disease Control and Prevention recommends at least seven hours of sleep per night for adults [7].

1. (2006) Extent and Health Consequences of Chronic Sleep Loss and Sleep Disorders. In Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem [HR Colten and BM Altevogt, editors]. Washington (DC).
2. Sprecher KE, Koscik RL, Carlsson CM et al. (2017) Poor sleep is associated with CSF biomarkers of amyloid pathology in cognitively normal adults. Neurology.
3. Mander BA, Marks SM, Vogel JW et al. (2015) beta-amyloid disrupts human NREM slow waves and related hippocampus-dependent memory consolidation. Nat Neurosci 18, 1051-1057.
4. Xie L, Kang H, Xu Q et al. (2013) Sleep drives metabolite clearance from the adult brain. Science 342, 373-377.
5. Su YS, Ooms SJ, Sutphen C et al. (2017) Slow wave sleep disruption increases cerebrospinal fluid amyloid-β levels. Brain.
6. Schneider L (2015) Safety and efficacy of piromelatine in mild Alzheimer's disease patients (ReCOGNITION). ClinicalTrials.gov.
7. (2017) Are you getting enough sleep? CDC.

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