Sleep apnea causes microbleeds in the brain over time

Microbleeds in the brain can be added to the list of concerns arising as a risk from obstructive sleep apnea (OSA).A study found that over an eight-year period patients diagnosed with moderate to severe OSA had an increased risk for cerebral microbleeds (CMBs) compared to a similar cohort with mild or no OSA. Findings were published in JAMA Network Open.The presence of CMBs is important because they are an early marker of cerebral vasculopathy and are associated with increased risk for stroke and dementia. They are not uncommon. Indeed, according to the study, “The prevalence of CMBs in the general population varies from 3% in middle-aged individuals to as high as 23% in older individuals.” This can increase to 50%-to-70% in patients with known cerebrovascular disease. The authors noted that the incidence of stroke is increasing in younger and middle-aged people, making it even more important to understand underlying relationships and causes.OSA is already known to be correlated with cardio- and cerebrovascular diseases such as arrhythmia, myocardial infarction, cerebral small vessel disease and stroke. But what has not been well established is its association with CMBs. Evidence for a connection has been mixed, largely because studies have been small or did not look for this specifically. CMBs are increasingly recognized as a potentially important player because more studies point to them as being associated with accelerated cognitive decline and dementia in the general population. When it comes to prevention or modifiable risk factors, the only ones known associated with CMBs thus far are smoking, hypertension, dyslipidemia, diabetes, and the presence of cardiocerebrovascular diseases, the study said.But now, treating OSA could be added to the list.The study was designed to help answer the question whether OSA severity is associated with a risk of incident CMBs in a late middle-aged general population over time. The researchers drew on data from the Korean Genome and Epidemiology Study (KoGES), an ongoing, long-term prospective population study. Baseline clinical examinations were conducted between 2011 and 2014, and questionnaires were used to collect demographic, lifestyle, health status and other details. A total of 2,918 participants with underwent home-based, unattended polysomnography (PSG). The participants then underwent follow-up examinations at four-year intervals. Two additional follow-ups when PSG was again conducted in 2015 to 2018, and 2019 to 2022. Participants also underwent brain magnetic resonance imaging (MRI) examinations at different points in time. After exclusions, such as microbleeds present at baseline, it was found that 1,441 participants had both PSG and MRI data, and these were the subjects included in the analyses.Apnea was defined as being when airflow decreased by 90% of the baseline or greater for at least 10 seconds. Microbleeds were identified as well-defined, homogenous, hypointense lesions of less than 10mm.The study included 1,441 participants with a mean age of 57.75 at baseline. Of these, 759 (52.67%) were female. A total of 436 (30.25%) participants had mild OSA at baseline and 193 (13.39%) participants had moderate to severe OSA. The other 812 participants had no OSA. The moderate to severe OSA group had a higher proportion of current smokers and current drinkers. Hypertension and diabetes were proportionately more frequent in the moderate to severe group. Mean serum total cholesterol levels also differed significantly between moderate to severe and non-OSA groups being an average of 194.5 mg/dL versus 202.8 mg/dL respectively, but not between the moderate to severe and mild OSA groups.At the four year mark, similar rates of CMBs were found in the non-OSA and mild OSA cohorts: 15 out of 812 people with no-OSA, or 1.85%; and 7 out of 426 people with mild OSA or1.61%. But the numbers were significantly higher in the moderate to severe OSA group, impacting nine, or 4.66% of patients.However, at the eight-year mark, the rate of CMBs in the non and mild OSA groups both hovered at about 3.2% of the patients. The rate jumped to 7.25% of the moderate to severe group.Even after adjusting for other risk factors such as smoking, hypertension, cholesterol levels and other factors, the risk for CMBs was still significantly higher in the moderate to severe group. At eight years, the moderate to severe groups had a 2.9% increased likelihood of having CMBs than the non and mild OSA groups. But after these adjustments there was no significantly increased risk at the four-year mark.“Mild OSA was not found to be associated with increased risk of CMBs at any follow-up period.,” the authors wrote.According to Toronto-based sleep researcher and neurologist, Dr. Mark Boulos “the discovery here that sleep apnea might be linked to microbleeds is a big finding . . . it’s an important step forward.” Dr. Boulos is an associate professor of medicine at the University of Toronto. While he is researching the same area, he was not involved in this study. He and his team published a review on the topic in Chest in 2024.The finding could have clinical implications. “We know we can treat sleep apnea and presumably that may help improve people’s outcomes in the long run,” he told the Canadian Healthcare Network. Sleep apnea appears to increase the risk of brain bleeds via a number of possible mechanisms. One is that OSA increases blood pressure in the body and in the brain, and this increase can potentially cause bleeding in the brain.“Sleep apnea can also drop the oxygen in the brain and throughout the body, leading to hypoxemia. That can make the blood vessels more susceptible and potentially can cause bleeding in the brain as well,” he said.There are also intrathoracic changes which can occur in the brain and can also be risk factors for harmful effects on the blood vessels by putting additional strain on them.He noted that cerebral microbleeds are risk factors for big bleeds which can have devastating impacts on patients.

Sleep apnea causes microbleeds in the brain over time

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