A study found that obstructive sleep apnea blocks the brain's waste clearance and raises the risk of Alzheimer's disease. Sleep apnea occurs when the airway narrows during sleep and temporarily stops breathing, affecting not only daily life but also cognitive function.
A team led by Yoon Chang-ho, a neurology professor at Seoul National University Bundang Hospital, and Robert Thomas of Harvard Medical School said, "Patients with sleep apnea have lower scores on the glymphatic activity index," in the latest issue of the American Journal of Respiratory and Critical Care Medicine.
The researchers followed 1,110 adults who took part in the Korean Genome and Epidemiology Study for an average of 4.2 years. They found that patients with sleep apnea had lower scores on the glymphatic activity index observed on MRI (magnetic resonance imaging). The glymphatic system expels waste that accumulates in the brain, including beta-amyloid, which causes Alzheimer's disease. It is most active during deep sleep.
Patients with sleep apnea were unable to sleep properly, and their brain's waste clearance function declined. Like a clogged drain, waste accumulated in the brain and cognitive function fell. Visual memory scores that assess how well a person remembers faces and scenes also decreased. The researchers said, "Sleep apnea impairs glymphatic function and indirectly affects cognitive function."
By contrast, patients whose sleep apnea was treated with positive airway pressure showed higher glymphatic activity index scores. Memory also recovered. A positive airway pressure device is a medical device worn like a mask that blows compressed air through the nose during sleep. The researchers said positive airway pressure treatment is needed to prevent Alzheimer's disease in patients with sleep apnea.
Sleep apnea affects about 1 billion people worldwide. It occurs more often with age and in those who are overweight. Yoon said, "Sleeping well is the way to protect brain health."
References
American Journal of Respiratory and Critical Care Medicine (2025), DOI: https://doi.org/10.1164/rccm.202411-2221OC