A new study from Korea University Ansan Hospital has found that moderate to severe obstructive sleep apnea could increase the risk of tiny brain bleeds, known as cerebral microbleeds.
These small spots, which show up on MRI scans, are early signs of brain damage and have been linked to conditions like stroke and dementia.
The study, published in JAMA Network Open, focused on middle-aged and older adults. Researchers wanted to find out whether the severity of sleep apnea—a condition where breathing stops and starts during sleep—might be connected to future brain problems. Earlier studies had mixed results, so this team set out to do a more in-depth investigation.
To do this, researchers followed 1,441 people from a Korean community. None of them had microbleeds or serious heart or brain problems at the start. Participants had sleep tests done in their homes and brain scans taken at the beginning of the study and again over time.
The people were grouped by the severity of their sleep apnea: 812 had no sleep apnea, 436 had mild sleep apnea, and 193 had moderate to severe sleep apnea. The severity was based on how many times per hour their breathing stopped or slowed—less than 5 times per hour was considered no sleep apnea, 5 to 14.9 was mild, and 15 or more was moderate to severe.
After four years, 4.66% of people with moderate to severe sleep apnea had developed microbleeds. That number rose to 7.25% after eight years. In contrast, only 1.85% and 3.33% of those without sleep apnea had microbleeds at four and eight years, respectively.
This means that people with more serious sleep apnea had more than twice the risk of developing brain bleeds than those without sleep apnea.
The researchers also looked at whether having a specific gene, APOE-ε4—which is known to raise the risk for brain and blood vessel problems—would change the results. About 19% of the participants had this gene.
Even after considering this genetic risk, the link between moderate to severe sleep apnea and brain bleeds stayed strong. This means that sleep apnea itself is likely a key risk factor, not just genetics.
Interestingly, people with mild sleep apnea did not show a significantly higher risk of microbleeds at any point in the study. And while the risk for those with moderate to severe sleep apnea wasn’t clearly higher after four years, it became very clear by eight years.
The researchers say these findings are important because cerebral microbleeds can be early warning signs of bigger problems like stroke or dementia. Since sleep apnea is treatable, it could be an important condition to screen for—especially in older adults—so that early treatment might prevent future brain damage.
In conclusion, moderate to severe obstructive sleep apnea appears to raise the risk of brain microbleeds over time, and this risk is not simply due to genetics. This makes sleep apnea a modifiable risk factor that doctors may want to monitor more closely in aging populations.
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The study is published in JAMA Network Open.
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