Obstructive sleep apnea (OSA) is a sleep disorder that causes a person to briefly and repeatedly stop breathing in his or her sleep. You may not know this, but the issue may actually lead to numerous health ailments, with one recent study finding that obstructive sleep apnea appears to increase one’s odds of developing Alzheimer’s disease. Yikes.
Sleep apnea occurs when the muscles in the back of the throat fail to keep the airway open even as the body works to keep breathing. More than 18 million adults in the United States have OSA and either experience or are at a higher risk of experiencing high blood pressure, heart disease, and mood and memory problems (Alzheimer’s disease) due to the disorder.
For the study, lead researcher neurologist Dr. Diego Carvalho and his colleagues looked at 288 adults, aged 65 and older, who did not have thinking or memory problems. The participants underwent brain scans to determine if they had “tau protein tangles” in the temporal lobe, the part of the brain involved in memory and perception of time. The temporal lobe is more likely to accumulate tau tangles than other areas of the brain.
In addition, the researchers asked the participants’ bed partners if they had ever seen them experiencing sleep apnea; 43 individuals with symptoms were identified.
Those adults were found to have more than 5% more tau than those without sleep apnea symptoms. That finding remained consistent after the team adjusted for other factors linked to tau accumulation, including age, sex, education, cardiovascular risk factors, and other sleep problems.
“Since tau accumulation is a hallmark of Alzheimer’s disease, an increase in tau raises concern that sleep apnea could make [people] with sleep apnea more vulnerable to Alzheimer’s.”
The study backs previous studies suggesting that sleep apnea increases the risk of dementia.
“However, it is also possible that Alzheimer’s disease could predispose people to sleep apnea or that there is a bidirectional relationship between sleep apnea and Alzheimer’s disease.”
The study was limited by the small number of participants, the lack of tests to confirm a diagnosis of sleep apnea and uncertainty over whether any of the participants were already being treated for it.
Researchers haven’t identified the mechanism behind sleep apnea’s apparent influence on Alzheimer’s risk, and don’t know if sleep apnea causes the buildup of “tau” protein tangles in the brain that are a marker for Alzheimer’s, or if the increased tau contributes to sleep apnea.
However, they suspect that the brain experiences excess stress due to less oxygen getting to the organ during apnea episodes. Sleep disturbances may also disrupt the brain’s circadian rhythms, the internal “body clock” that cycles between alertness and sleepiness.
The brain solidifies memories during sleep, Rebecca Edelmayer, director of scientific engagement at the Alzheimer’s Association, who reviewed the study, said. Interrupting that process may have a negative effect on both memory and thinking.
“What we know now about the importance of sleep is that good sleep is really important for your overall health,” said Edelmayer.
The findings are slated to be presented at an AAN meeting in Philadelphia on May 4. Research presented at meetings is typically considered preliminary until published in a peer-reviewed journal.