Sleep Apnea Linked to Dementia in Older Women

An article featured in the Denver Post this summer addressed the link between sleep apnea and dementia. Here's what the article had to say:

   Older women with sleep apnea have twice the risk of developing dementia as those without the breathing disorder, according to a study published Tuesday, but the data weren't conclusive as to why.

   The findings indicate that people with sleep apnea should be screened for cognitive problems, said Kristine Yaffe, an author of the study in JAMA: the Journal of the American Medical Association.

   Potential cognitive decline "is another reason why you want to be medically followed carefully and possibly treated" for sleep apnea, said Dr. Yaffe, who is a professor of psychiatry, neurology and epidemiology at the University of California, San Francisco.

   Sleep apnea, in which sufferers stop breathing as many as hundreds of times a night, commonly results from a blockage of the airway during sleep. The disorder is estimated to affect 10% to 20% of middle-aged and older adults, according to a recent report by the federal Agency for Healthcare Research and Quality.

   The study published Tuesday followed 298 older women who all started off testing cognitively normal. They had a mean age of 82 and were followed for an average of five years. Over that time, the women who had sleep apnea were twice as likely to develop memory decline or other symptoms of dementia.

   When a person stops breathing during sleep, blood-oxygenation levels fall. When it reaches a certain low, the body wakes itself and begins breathing again. To get a diagnosis of sleep apnea, such episodes must occur five or more times per hour. Typically a person with sleep apnea isn't aware this is happening but feels tired upon waking despite getting many hours of sleep.

   The increased risk of dementia appeared linked to the amount of time the women experienced decreased oxygen, not the total amount of sleep or the number of interruptions to their sleep. It isn't definitive from the data, however, whether oxygen deprivation caused the dementia symptoms or some other pathology was responsible for both the sleep problems and the cognitive decline. The results would likely apply to men as well but need to be replicated in that population, Dr. Yaffe said.

   The study examined women with moderate sleep apnea - 15 or more breathing stoppages per hour - so the cognitive impact among those with milder sleep apnea wasn't clear, said Amy Aronsky, medical director for the Center for Sleep Disorders in Longview, Wash., who wasn't involved with the study. However, the finding "gives further proof to the idea that untreated sleep apnea has a lot of unintended consequences", Dr. Aronsky said.

This article was written by Shirley S. Wang