Better Sleep for a Stronger Mind

Dementia risk may be higher in elderly sleep apnea patients who do not get enough deep sleep

(RxWiki News) A good night’s rest may not only make you less groggy — it could also prevent a more serious brain drain. Those who get enough deep sleep may be less likely to develop dementia.

A new study found that elderly patients who had sleep apnea and a lack of regular deep sleep had a raised risk of brain cell damage that has been linked to dementia and Alzheimer’s disease.

"This is one of several studies that have demonstrated damage to the brain as a result of sleep apnea or insufficient sleep," said Robert S. Rosenberg, DO, FCCP, Medical Director of the Sleep Disorders Center of Prescott Valley, Arizona and sleep medicine consultant for Mountain Heart Health Services in Flagstaff, Arizona.

"Brain imaging studies such as MRIs are useful in demonstrating these negative effects. The good news is that much of this is reversible when treated," said Dr. Rosenberg, who is author of "Sleep Soundly Every Night; Feel Fantastic Every Day."

The authors of this study said that getting good sleep through treatment — such as with a continuous positive airway pressure machine to treat sleep apnea — could lower patients' risk of cognitive problems.

"[Our] findings suggest that low blood oxygen levels and reduced slow wave sleep may contribute to the processes that lead to cognitive decline and dementia,” said lead study author Rebecca P. Gelber, MD, DrPH, of the VA Pacific Islands Health Care System and the Pacific Health Research and Education Institute in Honolulu, Hawaii, in a press release.

These researchers studied 167 Japanese-American men. These men were 84 years old on average at the start of the research when sleep testing began. They were followed until the ends of their lives, an average of six years from the study's start. Autopsies on the patients revealed changes in their brains.

Sleep disorders that deprive the body of oxygen may harm and change brain tissue. Sleep apnea, for instance, has been shown to damage brain cells. Sleep apnea is a sleep disorder in which breathing repeatedly stops. Loss of deep sleep may also lead to brain deterioration.

Patients were categorized into four groups based on how much oxygen they were getting during sleep. The group getting the least oxygen consisted of men spending 72 to 99 percent of the night with low blood oxygen levels. The group getting the most oxygen spent just 13 percent of the night or less with low blood oxygen levels.

Dr. Gelber and team found that four of the 41 men getting the most oxygen during the night had micro infarcts in the brain. Among the 42 getting the least oxygen, 14 had micro infarcts. Micro infarcts, in this case, are small areas of brain tissue that die due to a lack of oxygen.

These researchers also separated patients into groups based on how well they slept. Patients were again divided into groups based on how much time they spent in deep, or slow wave, sleep. Slow wave sleep is considered key for memory processing. The elderly typically have relatively short periods of slow wave sleep and fewer of them, according to the Division of Sleep Medicine at Harvard Medical School.

Brain cell loss was less likely among those who had the most deep sleep. Dr. Gelber and team observed that 17 of the 37 men who spent the least time in deep sleep had brain cell loss — compared to 7 of the 38 men who had the most time in deep sleep.

Dr. Gelber said that using a continuous positive airway pressure machine (CPAP) for obstructive sleep apnea may improve brain function, even after dementia has developed, based on results from a past study. Dementia is marked by a decline in brain function that affects memory, thinking, language, judgment and behavior.

"More research is needed to determine how slow wave sleep may play a restorative role in brain function and whether preventing low blood oxygen levels may reduce the risk of dementia," Dr. Gelber said.

This study was published online Dec. 10 in the journal Neurology.

This research was funded by the National Institute on Aging, the Alzheimer’s Association, the Hawaii Community Foundation and Office of Research and Development and the Department of Veterans Affairs Pacific Islands Health Care. The authors disclosed no conflicts of interest.


Review Date: 
December 12, 2014