BY NOAH GLENN
Repeated pauses in breathing during sleep, also known as sleep-disordered breathing, are linked to cognitive dysfunction, especially among people with a genetic predisposition to Alzheimer's disease. That's according to a study published online July 21 in The Annals of the American Thoracic Society.
Measuring Sleep Quality
Researchers from a variety of institutions in the United States analyzed data on 1,752 participants in the MESA Sleep Ancillary Study. The ancillary study was part of the larger Multiethnic Study of Atherosclerosis (MESA), which was designed to examine cardiovascular health in more than 6,000 adults of diverse ethnic backgrounds from six communities in the US, between 2010 and 2013. The participants were 68 years old on average, and 45.4 percent were male. About a quarter of the participants carried the APOE ε4 gene, which is linked to a higher risk of developing Alzheimer's disease.
Participants in the ancillary study underwent an at-home polysomnography test (PSG), which detects a wide range of sleep metrics: abnormally low oxygen levels in blood, irregular breathing, the number of times sleepers transition to a lighter stage of sleep or wake up, sleep stages, and total sleep time.
The participants also completed a short questionnaire to assess daytime sleepiness, and were given several cognitive tests to evaluate their attention, concentration, and processing speed.
Sleep Disorders-Cognition Connection
Participants who had higher daytime sleepiness scores on the questionnaire and abnormally low levels of oxygen in the blood had lower cognitive test scores, particularly in attention and memory.
Furthermore, sleep apnea syndrome coupled with higher questionnaire scores also correlated to lower scores in attention and processing speed. The findings were consistent after the researchers adjusted for age, body mass index, hypertension, and diabetes.
Finally, participants who carried the APOE ε4 gene had the strongest correlation between daytime sleepiness, low levels of blood oxygen, and worse cognition, suggesting that the gene magnifies the effects of poor sleep on the brain.
Get Treatment for Sleep-Disordered Breathing
The findings suggest that sleep-disordered breathing and associated sleep problems increase the risk of cognitive problems, the study authors say. They also suggest that people with the APOE ε4 gene who have sleep-disordered breathing are at even greater risk of developing Alzheimer's disease.
If you experience sleep-disordered breathing, and especially if you know you also carry the APOE ε4 gene, you might want to talk with your doctor about treatment options.