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Wednesday 10 August 2011

Sleep apnea linked to memory decline, dementia

Tech and Science | Updated today at 10:30 AM


NEW YORK (Reuters) - OLDER women who have sleep apnea, which leads to abnormal pauses in breathing or abnormally low breathing during sleep, may be more likely to develop memory problems and dementia, according to a US study.

It's not clear whether treating sleep apnea, which is especially common in older, overweight people, would help prevent that memory decline, partly because clear answers have been lacking on the link between problem sleeping and memory.

But the study, which looked at nearly 300 women and was led by Kristine Yaffe of the University of California, San Francisco, found that a little over 45 per cent of women who had signs of sleep apnea in initial tests had developed mild cognitive impairment or dementia five years later.

By contrast, only 31 per cent of women who did not have sleep problems developed thinking and memory problems.

'Among older women, those with sleep-disordered breathing compared with those without sleep-disordered breathing had an increased risk of developing cognitive impairment,' wrote Ms Yaffe and her colleagues in the Journal of the American Medical Association.

Ms Yaffe and her team gave an overnight sleep apnea test to 298 women without dementia, who were an average of 82 years old. The test looks for changes in breathing and oxygen flow during the night, as well as for the short, frequent breaks in sleep that are signs of sleep apnea.

Just over a third of the women had the disorder.

About five years later, those same women were brought in for a set of thinking and memory tests, with doctors evaluating any of those who showed signs of memory decline.

When Ms Yaffe and her colleagues took factors such as race, weight and other diseases and medications into consideration, women with sleep apnea were almost twice as likely to test positive for cognitive impairment or dementia.

'It makes sense that good sleep is going to be protective to the brain,' said Robert Thomas, who studies sleep at Harvard Medical School in Boston and was not involved in the study.

'We simply don't have data to answer many of the simple questions people may have in the sleep clinic,' he told Reuters Health.

Sleep apnea has been linked to a host of other problems, including high blood pressure and cholesterol. Researchers pointed to lower blood flow to the brain during sleep as a possible culprit in cognitive problems down the line.

Indeed, when the authors looked at the specific factors that went into a diagnosis of sleep apnea, they found that the lack of steady oxygen overnight was related to thinking and memory problems, not how much total sleep women got or how many times they woke during the night.

Mr Thomas said that not everyone with sleep apnea has symptoms, which include fatigue and snoring, and that people who are overweight or have heart and blood pressure diseases should also consider getting tested.

But researchers still don't know to what extent treatment, which involves wearing a mask that delivers pressurised air from a 'CPAP' machine to ease breathing at night, can prevent the complications of sleep apnea, including cognitive decline.

'The biggest hole in sleep apnea (research) is: what are the outcomes of treatment?' Mr Thomas said.

Ms Yaffe agreed. 'That's obviously a next step and an important question.'

Ref; ST news - Posted using BlogPress from my 4GiPhone

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