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Sleep apnea and brain health

Consequences of sleep apnea

Sleep apnea is a medical condition in which breathing repeatedly stops and starts during sleep, leading to low oxygen levels and poor sleep quality. It leads to sleepiness, poor memory and impaired concentration. Moreover, it leads to an increased risk of having a stroke or developing dementia over time.

The key questions are: How is sleep apnea damaging the brain, and how can we prevent or reverse this damage?

Sleep apnea-related brain damage: what we already know

We already know a bit about how sleep apnea affects the brain. We know that sleep apnea decreases the amount of deep sleep, and that this may impair the clearance of toxic proteins from the brain. This may be one reason why sleep apnea appears to be associated with impaired clearance of amyloid-beta, the toxic protein that builds up in Alzheimer’s disease. We also know that patients with sleep apnea have shrinkage in certain brain regions and damage to the white matter of the brain, which may disrupt connections between neurons. However, there is much that we do not know about how this happens.

Sleep apnea-related brain damage: what we need to find out

We think that sleep apnea causes brain damage by damaging brain blood vessels, altering blood flow to the organ and inhibiting clearance of toxins from the brain. This in turn may lead to damage to the brain grey matter, which is made of neurons, and white matter, the connections between neurons. We also think that these injuries to the brain circulation may be related in part to more general changes in body hormones and chemistry; regulation of the autonomic nervous system, which is responsible for the fight-or-flight response; blood pressure; inflammation and blood vessel stiffening.

The Brain Changes in Sleep Apnea Study will find out whether these ideas are true. In this study we will be doing the following:

  • using wearable sensors to measure sleep quality, autonomic nervous system function, oxygen levels and blood pressure—all in the comfort of your home.
  • getting blood and urine samples to measure hormone levels, metabolism and inflammation, and to examine genes related to sleep and brain health.
  • measuring your pulse to determine blood vessel stiffness.
  • using an MRI scan to measure damage to the blood vessels, grey and white matter in the brain, and brain blood flow.

Continuous positive airway pressure (CPAP)

The standard treatment for sleep apnea is continuous positive airway pressure (CPAP). This method works by gently blowing pressurized air through the airway at a constant pressure to prevent the throat from collapsing, which causes the pauses in breathing that characterize sleep apnea. We know that CPAP can improve some of the sleepiness that accompanies sleep apnea. However, we do not know if CPAP can prevent or reverse sleep apnea-associated brain damage. By repeating all the measurements before and after four months of CPAP, we can find out if CPAP is effective at treating the brain damage due to sleep apnea.

Toward new treatments for preventing sleep apnea-related brain damage

By participating in this study, you will help us to identify the specific ways that sleep apnea damages the brain. This may lead to new drugs, new uses for existing drugs or even nondrug therapies that target the specific mechanisms underlying sleep apnea-related brain damage (e.g., hormones, inflammation or the fight-or-flight response). In doing so, we may be able to prevent or reverse some of this damage. These drugs may supplement CPAP or may prove to be a way of preventing sleep apnea-related brain damage in the absence of CPAP.

Contact information

Email: sleepapneabrain@sunnybrook.ca
Telephone: 416-480-5143
Address: Sunnybrook Health Sciences Centre, 2075 Bayview Ave., M1 600, Toronto, ON M4N 3M5