Poor Sleep Linked to Brain Changes that Lead to Dementia

Amy Taylor December 15, 2014

People who have sleep apnoea or spend less time in deep sleep may be more likely to have changes in the brain associated with dementia, according to new research.

Researchers from VA Pacific Islands Health Care System and the Pacific Health Research and Education Institute in Honolulu, Hawaii, found that people who don’t have as much oxygen in their blood during sleep, which occurs with sleep apnoea and conditions such as emphysema, are more likely to have tiny abnormalities in brain tissue, called micro infarcts, than people with higher levels of oxygen in the blood.

For the study, the researchers recruited 167 Japanese-American men with an average age of 84, who had sleep tests conducted in their homes. All were followed until they died an average of six years later, and autopsies were conducted on their brains to look for micro infarcts, loss of brain cells, the plaques and tangles associated with Alzheimer’s disease, and Lewy bodies found in Lewy body dementia, the researchers report.

Participants were divided into four groups based on the percentage of time spent with lower than normal blood oxygen levels during sleep. The lowest group spent 13 percent of their time or less with low oxygen levels, while the highest group spent 72 to 99 percent of the night with low oxygen levels. Each group had 41 or 42 men.

The results remained the same after adjusting for factors such as smoking and body mass index and after excluding participants who had died early in the follow-up period, and those who had low scores on cognitive tests at the beginning of the study, according to the researchers.

The new findings, published in the Neurology, the medical journal of the American Academy of Neurology, also suggest that people who spent less time in deep sleep, called slow wave sleep, were more likely to experience the loss of brain cells than people who spent more time in slow wave sleep. Loss of brain cells is also associated with Alzheimer’s disease and dementia.

“These 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 study author Rebecca P. Gelber, M.D., D.Ph.

“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.”

Source of this article: Poor Sleep Tied to Dementia Changes