Study links obstructive sleep apnea to increased risk of dementia in women

A common but undiagnosed sleep disorder that contributes to the development of dementia in adults. especially in women, suggests the Michigan Medicine study.

Researchers found this by analyzing survey and cognitive screening data from more than 18,500 adults to determine the potential impact of known or suspected obstructive sleep apnea on dementia risk.

Obstructive sleep apnea is a chronic sleep disorder characterized by episodes of impaired or restricted breathing during sleep.

For all adults 50 years of age and older who have been diagnosed with obstructive sleep apnea or its symptoms -; because people often don’t know they have a problem -; was associated with a greater risk of developing symptoms or being diagnosed with dementia in the coming years.

Although the overall difference in dementia diagnoses never increased above 5%, the association remained statistically significant even after researchers accounted for many other factors that can influence dementia risk, such as race and education.

At all age levels, women with known or suspected sleep apnea had a higher risk of dementia than men.

In fact, the rate of dementia diagnosis decreased among men and increased among women with age.

The results are published in Sleep progress.

“Our findings provide modern insight into the role of treatable sleep disorders on long-term cognitive health at the population level for both women and men,” said first author Tiffany J. Braley, MD, MS, neurologist, director of the Multiple Sclerosis Center/Department of Neuroimmunology and co-founder of the Multidisciplinary Fatigue and Sleep Clinic in MS at the University of Michigan Health.

Researchers say the reasons for gender differences in dementia diagnosis based on sleep apnea status are not yet known. However, they offer several possible explanations.

Women with moderate sleep apnea may be at greater risk of cardiovascular disease and are more likely to suffer from insomnia, which can negatively impact cognitive function.

As women enter menopause, estrogen levels begin to drop, which can affect their brains. During this time, they are more susceptible to changes in memory, sleep and mood, which can lead to cognitive decline. Sleep apnea significantly worsens after menopause, although it remains underdiagnosed. We need more epidemiological studies to better understand how sleep disorders in women affect their cognitive health.”

Galit Levi Dunietz, Ph.D., MPH, co-author, associate professor at the Department of Neurology and the Department of Sleep Medicine at the University of Michigan

Six million Americans have been officially diagnosed with sleep apnea, although the condition is thought to affect approximately 30 million people.

In the 2024 report Lancet The commission identified several modifiable risk factors that together account for approximately 40% of dementia cases worldwide.

Although sleep was not included as an official risk factor, the committee noted that sleep apnea “may be associated with dementia” and considered adding dementia screening questions for people with sleep disorders.

Other modifiable risk factors for dementia include cardiovascular disease and mental health problems, which can be exacerbated by untreated sleep apnea.

“These potential harms from sleep apnea, many of which are threatening and cognitive decline, underscore the importance of early diagnosis and treatment,” Braley said.

“Obstructive sleep apnea and the resulting sleep deprivation and fragmentation are also associated with inflammatory changes in the brain that may contribute to cognitive impairment.”

The Michigan Medicine study used existing data from the Health and Retirement Study, an ongoing survey representative of Americans age 50 and older.

“This study design cannot fully prove that sleep apnea causes dementia; “it would likely require a multi-year randomized trial comparing the effects of treating sleep apnea with the effects of no treatment,” said co-author Ronald D. Chervin, M.D., chief of the Division of Sleep Medicine in the Department of Neurology at UM Health.

“Because such a study can take a long time, if at all, to be conducted, retrospective analyzes such as ours, conducted on enormous databases, may prove to be among the most informative in the coming years. Meanwhile, the results provide modern evidence that clinicians and patients should consider the possibility that untreated sleep apnea causes or worsens dementia when making decisions about sleep apnea testing and treatment.”