Obstructive Sleep Apnea Is Associated with Higher Brain Amyloid

by | Dec 7, 2020 | 2020, Alzheimer's Disease, Brain Health, Sleep

Written by Joyce Smith, BS. Severe obstructive sleep apnea was associated with an increase in brain amyloid beta (Aß) protein and a greater risk of developing dementia.

man sleepingOSA is a common sleep disorder, affecting about 1 billion people worldwide 1 and can be 2-3 times more prevalent in those 65 years of age or older 2.  It is due to the collapse of the airway during sleep, resulting in intermittent dips in oxygen levels and arousals from sleep and when left untreated, can cause Aß deposits in the brain, which along with a reduction in grey matter volume, increases the risk of dementia 3. Approximately 38–45% of dementia patients have OSA 4 and according to longitudinal studies, OSA can develop into mild cognitive impairment (MCI) 5,6, Alzheimer’s disease (AD), and vascular dementia 7.

A causal link between OSA and dementia has never been established; therefore, the present study 8 was conducted to compare brain Aß burden in OSA individuals with healthy controls, and to explore potential associations between Aß burden and polysomnographic and subjective measures of sleep, demographics, and mood. An Australian research team assessed 34 participants with recently diagnosed untreated OSA (mean age of 57.5 years; 19 males) and 12 controls who were asymptomatic for sleep disorders (mean age 58.5 years; 6 males). All participants were required to undergo a clinical polysomnogram and an 11C-PiB positron emission tomography (PET) scan to quantify their amyloid burden. Secondary analysis compared amyloid burden between mild/moderate cases and severe cases of OSA.

Notable findings were as follows:

  • Researchers found an association between global Aß burden and age for both groups (p < 0.001).
  • Compared to the control group, amyloid burden was elevated in the OSA group (p = 0.05) and was significantly higher in those with severe OSA compared to those with mild/moderate OSA. (p = 0.002).
  • The association between APOE status and amyloid burden was not significant (p = 0.100) even after controlling for age (p = 0.055).
  • When controlling for age, higher Aß burden was associated with a higher non-rapid eye movement apnea hypopnea index (NREM AHI) (p=0.027), poorer sleep quality (p = 0.037), and less time spent in stage N3 sleep. (N3 sleep is a regenerative period of sleep where the body heals and repairs itself) (p = 0.04).

This preliminary study found an association between relatively young (mean age 57.5 years ) participants with untreated, clinically-diagnosed severe OSA and a modest elevation of brain Aß, the significance of which should be further investigated to explore the implications for dementia risk. The study does not prove causation; yet, while OSA can be readily treated with continuous positive airway pressure, recent evidence suggests that early intervention might weaken the association between OSA severity and Aß burden 9 and possibly prevent progression to Alzheimer’s disease in later life.

Source: Jackson, Melinda L., Marina Cavuoto, Rachel Schembri, Vincent Doré, Victor L. Villemagne, Maree Barnes, Fergal J. O’Donoghue, Christopher C. Rowe, and Stephen R. Robinson. “Severe obstructive sleep apnea is associated with higher brain amyloid burden: a preliminary PET imaging study.” Journal of Alzheimer’s Disease Preprint (2020): 1-7.

© 2020 – IOS Press and the authors. All rights reserved

Posted December 7, 2020.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

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