A common but underdiagnosed sleep disorder contributes to the development of dementia among adults -? especially women, suggests a Michigan Medicine study.
The researchers discovered this by examining survey and cognitive control 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 disrupted or restricted breathing during sleep.
For all adults aged 50 and over with known obstructive sleep apnea or its symptoms – as people often don’t know they have the problem -; was associated with a greater likelihood of developing signs or being diagnosed with dementia in subsequent years.
While the overall difference in these dementia diagnoses never exceeded 5 percent, the association remained statistically significant even after the researchers accounted for many other factors that can influence dementia risk, such as race and education.
At each age level, women with known or suspected sleep apnea were more likely than men to be diagnosed with dementia.
In fact, the rate of dementia diagnosis decreased among men and became greater for women as they aged.
The results are published in SLEEP proceeds.
“Our findings provide new insight into the role of a treatable sleep disorder in long-term cognitive health at the population level for both women and men,” said first author Tiffany J. Braley, MD, MS, neurologist, director of Multiple Sclerosis /Department of Neuroimmunology and co-founder of the Multidisciplinary MS Fatigue and Sleep Clinic at Michigan Health University.
The reasons for the sex-specific differences in the diagnosis of dementia from the sleep apnea condition, the researchers say, are not yet known. However, they provide several possible explanations.
Women with moderate sleep apnea may have a higher risk of cardiovascular disease and are more likely to have insomnia, both of which can negatively affect cognitive function.
Estrogen begins to decline as women go through menopause, which can affect their brain. During this time, they are more prone to changes in memory, sleep and mood that can lead to cognitive decline. Sleep apnea increases significantly after menopause, but 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 in the University of Michigan Department of Neurology and Department of Sleep Medicine
Six million Americans have been officially diagnosed with sleep apnea, yet the disorder is believed to affect nearly 30 million people.
In a 2024 report, a Lancet The Commission identified several modifiable risk factors that together account for approximately 40% of global dementia.
Although sleep was not included as a formal risk factor, the panel noted that sleep apnea “may be associated with dementia” and to consider adding dementia screening questions for people with the sleep disorder.
Other modifiable risk factors for dementia include cardiovascular disease and mental health problems, both of which can be worsened by untreated sleep apnea.
“These potential harms caused by sleep apnea, many of which threaten cognitive performance and decline, underscore the importance of early diagnosis and treatment,” Braley said.
“Obstructive sleep apnea and subsequent 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 that is representative of Americans age 50 and older.
“This study design cannot fully prove that sleep apnea causes dementia—that would probably require a randomized trial, over many years, to compare the effects of sleep apnea treatment with the effects of no treatment,” said co-author Ronald D. Chervin. MD, MS, director of the Division of Sleep Medicine in the Department of Neurology at UM Health.
“As it may be a long time before such a test is performed, analyzes such as ours, on large databases, may be among the most informative for years to come. Meanwhile, the results provide new evidence that clinicians and patients, when making decisions about sleep apnea management and treatment, should consider the possibility that untreated sleep apnea causes or worsens dementia. ».
Source:
Journal Reference:
Braley, TJ, et al. (2024). Risk of dementia by gender in known or suspected obstructive sleep apnea: A 10-year longitudinal population-based study. SLEEP proceeds. doi.org/10.1093/sleepadvances/zpae077.
