New York researchers have found a link between sleep apnea and high levels of the amyloid protein that is associated with Alzheimer’s disease.
The connection indicates that doctors should check for sleep apnea in older people who display no Alzheimer’s symptoms, the team said.
The study, published in the American Journal of Respiratory and Critical Care Medicine, dealt with obstructive sleep apnea, or OSA, the form of the disorder that causes a person’s breathing to become shallow or to stop while they are asleep. The title of the study is “Obstructive Sleep Apnea Severity Affects Amyloid Burden in Cognitively Normal Elderly: A Longitudinal Study.”
“Several studies have suggested that sleep disturbances might contribute to amyloid deposits and accelerate cognitive decline in those at risk” for Alzheimer’s, Dr. Ricardo S. Osorio an assistant professor of psychiatry at New York University School of Medicine, said in a press release. “However, so far it has been challenging to verify causality for these associations” obstructive sleep apnea and Alzheimer’s “share risk factors and commonly co-exist,” said Osorio, the senior author of the study.
The researchers checked 208 healthy people aged 55 to 90 with normal cognition for sleep apnea. The team also measured amyloid beta levels in participants’ cerebrospinal fluid. And they used position emission tomography scans to measure amyloid beta clumping in participants’ brains.
More than half of the participants had obstructive sleep apnea, the researchers discovered. Thirty-seven percent had mild cases and 17 percent moderate to severe cases. The higher the level of amyloid beta in participants’ cerebrospinal fluid, the worse their sleep apnea, the team found.
Dr. Andrew Varga, who specializes in sleep medicine and neurology at the Icahn School of Medicine at Mount Sinai in New York, said researchers failed to find a relationship between sleep apnea, amyloid beta levels and cognition. This suggests that cognition “is dependent on additional factors,” said Varga, a co-author of the study.
Since the severity of participants’ sleep apnea was not a predictor of cognitive deterioration, the study suggested that the changes in sleep patterns and amyloid beta levels that researchers spotted were occurring before participants developed signs of Alzheimer’s.
This prompted the team to suggest that addressing sleep apnea in its early stages could reduce the number of amyloid beta deposits occurring in the brain and consequently delay cognitive impairment and dementia.
Altogether, the results support “the growing literature suggesting that OSA, cognitive decline” and Alzheimer’s are related, Osorio said. “If this is the case, then the potential benefit of developing better screening tools to diagnose OSA in the elderly who are often asymptomatic is enormous.”