WEDNESDAY, March 25, 2020 (HealthDay News) -- New research out of France suggests that untreated sleep apnea could raise your odds for developing Alzheimer's disease.

Evidence linking the two is based on a series of neurological assessments, brain scans and sleep analyses conducted between 2016 and 2018.

"This is further support of Alzheimer's as a lifestyle chronic condition that results from a lifetime of experiences," said George Perry, chairman of neurobiology at University of Texas at San Antonio, who reviewed the findings.

The new research -- led by Gaël Chételat of the Cyceron Center in Caen, France -- focused on 127 older people, whose average age was 69. None displayed any outward sign of dementia or thinking problems at the time of the study.

Chételat's team first reviewed brain imagery to look for signs of beta-amyloid plaque in brain areas associated with Alzheimer's. An abnormal build-up of this naturally occurring protein is known to be tied to dementia risk. The same brain areas were also analyzed for signs of neurological activity linked to Alzheimer's.

Using portable home sleep trackers, the researchers found that roughly three-quarters of participants had breathing interruptions as they slept.

A well-known example of what the study called sleep-disordered breathing is sleep apnea, in which breathing repeatedly pauses for 10 seconds or more. Many patients use a device called a CPAP machine to prevent airway blockages that cause the start-and-stop breathing.

None of the study participants had been treated for a sleep disorder.

The research team found that untreated sleep-disordered breathing was associated with more of the early changes in brain structure and activity that boost Alzheimer's risk.

Two North American researchers who reviewed the findings said the conclusions make sense.

"Sleep is thought of as a period of brain recharge," said Perry. "And less-effective sleep will lead to reduced amyloid removal and oxygenation. Both of these changes are detrimental to brain metabolism."

Dr. Tetyana Kendzerska, an assistant professor of medicine at the University of Ottawa in Canada, said the pool of people for whom the findings might be concerning could be enormous. She said sleep-disordered breathing affects about one-quarter of adults.

Chételat and her team suggested that their findings "highlight the need to treat sleep disorders in the older population," even in the absence of any obvious signs of dementia or Alzheimer's.

But is it actually clear that a sleeping disorder can directly cause Alzheimer's risk to go up? Or that by tackling and treating something like sleep apnea one might effectively lower long-term dementia risk?

Kendzerska said the jury is still out.

"We still don't know yet given current evidence," she said. "This is a possibility to be tested in future studies."

The findings were reported online March 23 in JAMA Neurology.

More information

To learn more about Alzheimer's risk, visit the Alzheimer's Association.