A new study on sleep apnea, a nighttime breathing disorder often marked by snoring, underscores how sleep troubles may be linked to an increased risk of Alzheimer’s disease. Researchers found that the brains of people with sleep apnea had high levels of beta-amyloid plaques, a hallmark of Alzheimer’s disease.
In sleep apnea, people stop breathing for brief periods throughout the night, sometimes hundreds of times, causing them to wake up feeling unrefreshed and tired throughout the day. The condition affects almost one in 10 women, and one in four men, most of them middle-aged and older. Many people don’t even know they have the condition.
Snoring, gasping or grunting for air during sleep, or waking up tired no matter how long you sleep, can all be signs of sleep apnea. Other clues include feeling sleepy throughout the day, falling asleep within 10 minutes of starting to watch a movie or TV show, or feeling irritable and unfocused.
Scientists had long suspected links between sleep disorders such as sleep apnea and Alzheimer’s disease, and other studies have shown that poor sleep is linked to increased risk of the illness. But “our study is the first to find Alzheimer’s-like amyloid plaques in the brains of people with clinically-verified obstructive sleep apnea,” said Stephen Robinson, the study’s senior author and a professor at RMIT University in Australia.
“We know that if you have sleep apnea in mid-life, you’re more likely to develop Alzheimer’s when you’re older,” Professor Robinson said. “And if you have Alzheimer’s, you are more likely to have sleep apnea than other people your age.”
For the study, researchers compared the brains of 34 people who had died of Alzheimer’s disease with the brains of 24 people who had sleep apnea. They found that amyloid plaques appeared in the same areas of the brain, including the hippocampus, affected by Alzheimer’s disease. And the more severe the apnea, the greater the number of plaques in the brain.
Obstructive sleep apnea is on the rise in part because of growing rates of obesity, which can cause fat-laden tissues in the tongue and throat to compress the airways when throat muscles relax during sleep. It affects up to half of seniors, particularly those who are overweight, though skinny people can have sleep apnea too. Weight loss may help the condition, though is no guarantee.
In addition to causing daytime sleepiness and fatigue, sleep apnea has been linked to medical conditions like heart disease, high blood pressure and diabetes. Poor sleep and sleep apnea have also been linked to general forgetfulness and memory problems. One reason why sleep apnea may cause memory problems is that the condition is associated with low blood oxygen levels, which would reduce oxygen supply to the brain.
The most effective treatment for the condition is to use a breathing device that delivers a steady stream of air through a special mask over the face and nose during sleep every night. The treatment, known as CPAP, for continuous positive airway pressure, can be cumbersome, but it is effective for relieving symptoms.
If you suspect that breathing problems during sleep may be contributing to memory and thinking problems, it is important to discuss this with your doctor. You may need to undergo a sleep study, in which your sleeping is monitored in a sleep lab for a night.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Jessica E. Owen; Bryndis Benedktsdottir; Elizabeth Cook; et al: “Alzheimer’s disease neuropathology in the hippocampus and brainstem of people with obstructive sleep apnea.” Sleep, Sept. 21, 2020