Sleep Apnea and Dementia

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New studies suggest that obstructive sleep apnea may contribute to dementia.

image of older man sleeping

Anyone who has known someone who suffers from sleep apnea knows that the disorder can be very disruptive to one’s physical and mental well-being. Unlike mere restlessness or insomnia, sleep apnea occurs when a person’s breathing and airflow to the brain is constantly disrupted in their sleep, often causing fits of gasping or snorting that briefly wakes the sleeper up, usually without them even noticing. 

Most doctors agree that sleep apnea can affect the body in ways that go beyond mere fatigue, increasing the risk of high blood pressure and possibly contributing to the risk of heart attack and stroke. Some new studies show that the disorder also has a connection to dementia. 

For example, a study that was just completed in spring 2021 by a team at Sunnybrook Health Sciences Centre in Toronto is showing there’s a relationship between obstructive sleep apnea and dementia. The study started as a means of examining if at-home sleep apnea monitors are suitable for use by people with dementia (they are), and then expanded to ask the question of whether or not people with dementia are more likely to experience sleep apnea. A new paper published by the American Academy of Neurology confirms that there is a correlation between the two disorders. 

                                            Dr. Mark Boulos

“If your dementia or cognitive impairment is worse, you tend to have more severe sleep apnea,” says Sunnybrook neurologist Dr. Mark Boulos, the lead investigator on the study. “We found that there’s a high prevalence of sleep apnea in patients with dementia. The prevalence is so high that we found that sleep apnea might actually be a modifiable risk factor with dementia.”

The study looked at over 60 patients from the Toronto area with an average age of 73 and a history of cognitive impairment. The researchers observed each participant’s sleep with sleep apnea monitors, which give the most objective picture of sleep quality.

Fifty-two percent of the participants were found to have obstructive sleep apnea. Furthermore, those with sleep apnea were 60 percent more likely to score lower on a cognitive test than those who didn’t experience disrupted sleep. 

Other studies, like those done by the Canadian Consortium on Neurodegeneration in Aging and Dr. Andrew Lim (also at Sunnybrook), have also shown that there is a relationship between disrupted sleep and dementia, though Boulos and his colleagues’ study is targeted specifically at sleep apnea.

The question that goes beyond the scope of this study is whether sleep apnea may cause dementia or vice versa, or if the two conditions are both likely to be caused by another common factor. There’s also the question of whether or not simply being overtired — be it from sleep apnea or other factors like anxiety-induced insomnia or ingesting caffeine before bedtime — in itself may be enough to impact cognition. 

Still, Boulos believes there is enough emerging evidence to suggest that sleep apnea may contribute to dementia. He recommends that individuals who suspect they may be experiencing sleep apnea get it taken care of well before they reach the age where dementia symptoms are likely to emerge. 

                         Photo Courtesy of Canva

Researchers from Michigan Medicine’s Sleep Disorders Centre also recently did a study of American Medicare beneficiaries who had been diagnosed with sleep apnea. Those who sought treatment for their apnea through a therapy called positive air pressure were significantly less likely to receive a dementia or cognitive impairment diagnosis within the next three years as compared to those who did not receive similar treatment.

As researchers continue to explore questions around how and why dementia and sleep apnea are connected, the good news right now is that sleep apnea can be easily diagnosed and treated. And, even if further studies find that there ultimately isn’t a causational relationship between dementia and sleep apnea, taking care of sleep apnea can nevertheless lead to better overall health, as it also has been found to have a connection to diabetes, obesity, and cardiovascular disease and can drastically affect mood and mental well-being. 

Sleep apnea can be treated with the aforementioned positive air pressure therapy through CPAP machines, which help a user to breathe with a flow of steady air pressure delivered through a mask that is worn throughout the night. Changing sleeping positions, wearing mouthguards, and improving exercise and nutrition can also help to alleviate sleep apnea, depending on its severity. 

“If someone has signs of disrupted sleep or any concerns about their sleep they should get evaluated right away,” Bolous says. “This is potentially a risk factor for dementia. The bottom line is, even if you don’t have dementia, you should go get it checked out because there are many things that are potentially reversible by treating sleep apnea.”