A new study has found that obstructive sleep apnea can affect oxygen levels during sleep and increase the risk of dementia.

The study also found that women may have a higher risk of obstructive sleep apnea than men.

However, experts emphasize that we have no evidence that obstructive sleep apnea causes dementia and that more research is needed to determine the relationship between the two.

A new study has found that people with obstructive sleep apnea are more likely to develop dementia, and the risk may be greater in women.

This new study raises some questions: how obstructive sleep apnea (which reduces the body's oxygen levels during sleep) may affect brain health in the long term.

"Obstructive sleep apnea is a common, underdiagnosed but treatable condition that is associated with significant pathological changes in the brain," study author Dr. Tiffany Joy Braley, an associate professor of neurology at the University of Michigan School of Health and co-founder of the Multiple Sclerosis Fatigue and Sleep Clinic, told Health magazine. "[These] overlap with many of the brain changes in people with cognitive decline and dementia."

In addition to simply finding a link between sleep apnea and dementia risk, the researchers also found that this link was more pronounced in women. Experts are still not sure why, but it may be related to an increased risk of cognitive problems in women.

Dr. Galit Levi Dunietz, an associate professor of neurology and sleep medicine at the University of Michigan and a co-author of the study, told Health magazine: "There are many reasons why women have a higher risk of dementia, including their longer life expectancy, differences in health behaviors and social determinants of health."

The study was published last month in the journal Sleep Advances.

Here's what experts think about the link between obstructive sleep apnea and dementia, and how to protect your cognitive health if you have a sleep disorder.

Experts say this is not the first study to establish a link between obstructive sleep apnea and dementia. However, Dr. Nitun Verma, a spokesperson for the American Academy of Sleep Medicine and a doctor of medicine and MBA, told Health magazine: "This new study provides [10-year] longitudinal data on 18,815 subjects, adding depth to the discussion."

The study participants included those from the "Health and Retirement Study" (HRS), a nationally representative sample of American adults.

This study was launched in 1992, and the participants were all over 50 years old and did not have dementia.

The researchers then tracked the diagnosed cases of dementia among the study participants and recorded who was diagnosed with obstructive sleep apnea or reported symptoms.

This allowed the researchers to "determine whether pre-existing signs of [obstructive sleep apnea] - even in the absence of a clinical diagnosis - could predict the likelihood of developing dementia in the future," Braley said.

The decision to include participants with suspected sleep apnea in the analysis is also significant because many Americans with this condition have not been diagnosed. In fact, it is estimated that about 30 million Americans have sleep apnea, but only about 6 million Americans have been diagnosed.

There are several factors that can explain this. First, sleep apnea symptoms often develop gradually and go unnoticed, Verma said. "The most common symptoms, such as snoring and daytime sleepiness, are easily overlooked or attributed to other causes." In addition, experts say that many Americans may not have access to a sleep study, which is necessary for diagnosing the condition.

After the researchers completed the analysis, they found that by the age of 80, the incidence of dementia was 4.7% higher in women with diagnosed or suspected sleep apnea, while it was 2.5% higher in men with diagnosed or suspected sleep apnea.

"Adults with obstructive sleep apnea have a higher risk of developing dementia in the future compared to adults with unknown or unsuspected obstructive sleep apnea, especially in women," Braley said.

Although the study did not investigate this, experts have proposed some theories about why sleep apnea may affect the risk of dementia.

First, sleep disorders can make it difficult to get a good quality of sleep. This increases the risk of cognitive problems.

"Recent evidence suggests that sleep deprivation or sleep loss (both of which are consequences of obstructive sleep apnea) are associated with an increased accumulation of pathological biomarkers related to Alzheimer's disease," Braley said.

Another possible explanation, she added, is that sleep apnea and sleep deprivation may alter the function of the immune system, making it more difficult for the body to clear toxic substances in the brain that are related to dementia.

As for why the association between sleep apnea and dementia is more pronounced in women than in men, hormonal differences may play a role, Dunietz explained.

"As women enter menopause, their estrogen levels decline, which may interact with sleep problems and increase the risk of dementia," she said.

Lack of access to quality care and gender differences in healthcare may also be contributing factors.

"An important factor is that women may be misdiagnosed or undiagnosed, which may prolong the time they suffer from not being treated [for sleep apnea]," Verma said. "More research is needed to better understand and analyze this relationship."

The new study emphasizes that if you suspect you have obstructive sleep apnea, you need to seek treatment.

"Identifying and addressing this impactful and treatable condition can be another step in supporting cognitive health," Braley said.

Common symptoms of sleep apnea include snoring, daytime sleepiness, fatigue, difficulty concentrating, headaches or waking up frequently in the middle of the night to go to the toilet.

Dr. Robson Capasso, a professor of otolaryngology and director of sleep surgery at Stanford Healthcare, said: "It's important to remember that there is currently no evidence that sleep apnea itself causes dementia."

He told Health magazine: "People shouldn't panic about this."

Although more research is needed on the link between sleep apnea and brain health, poor sleep is indeed a concern - sleep deprivation is associated with obesity, heart health problems and type 2 diabetes.

Therefore, Capasso said that if possible, people should try to address or mitigate any modifiable risk factors for sleep apnea, including excessive alcohol consumption, smoking and obesity.

Verma added that if you have already been diagnosed, it is important to track your symptoms and communicate with your doctor if they do not improve or worsen.

"Early identification, diagnosis and effective treatment of obstructive sleep apnea are crucial as they may help to mitigate adverse health consequences," he said.