People who spend less time in deep sleep tend to suffer from brain cell loss
Sleep apnea, also known as sleep-disordered breathing, can deprive the brain and other organs of oxygen, causing cognitive ability to decline over time. A study has shown that these people, and those who spend less time in deep sleep, may be more likely to suffer from changes in the brain that are associated with dementia.
People who don’t have the most oxygen in their blood during sleep, which occurs in apnea and conditions such as sleep emphysema, are more likely to suffer from small abnormalities in brain tissue, called microinfarctions, than individuals with higher levels of oxygen in their blood. These abnormalities are associated with the development of dementia.
In addition, people who spent less time in deep sleep, called slow-wave sleep, were more likely to suffer from brain cell loss than those who spent more time in slow-wave sleep. Slow-wave sleep is important in processing new memories and remembering facts, and people tend to spend less time in slow-wave sleep as they age. The loss of brain cells is also linked to Alzheimer’s disease and dementia.
For this study, 167 Japanese American men were sleep tested at home when they were an average of 84 years old and followed until they died an average of six years later. Autopsies of their brains were performed to look for microinfarctions, loss of brain cells, plaques and tangles associated with Alzheimer’s disease and Lewy bodies found in Lewy body dementia.
The researchers divided the participants into four groups, each with between 41 and 42 members, based on the percentage of time spent with lower-than-normal blood oxygen levels during sleep, with the lowest group spending 13 percent of the time or less with low oxygen levels and the highest being between 72 and 99 percent of the night with low oxygen levels.
Of the 41 men in the lowest group, four had microinfarctions in the brain, while 14 of the 42 men in the highest group had abnormalities, making them nearly four times more likely to suffer brain damage.
Sleep and lack of oxygen
Previous studies have also shown a link between sleep phases and dementia. For this work, participants were again divided into four groups based on the percentage of the night they were in slow-wave sleep. Of the 37 men who spent the least time in slow-wave sleep, 17 had brain cell loss, compared with seven of the 38 men who spent most of the time in slow-wave sleep.
The results were the same after adjusting for factors such as smoking and body mass index and after excluding participants who had died at the beginning of the follow-up period and those who had low scores on cognitive tests at the start of the study.
However, he believes more research is needed to determine how slow-wave sleep may play a restorative role in brain function and whether avoiding low blood oxygen levels can reduce the risk of dementia.
Gelber notes that an earlier study showed that using a continuous positive pressure (CPAP) machine for obstructive sleep apnea can improve cognition, even after dementia has developed. There was no association between sleep measurements and the level of plaques and tangles.
Source: La Opinión de Málaga
