The study found that obese participants with sleep apnea had significantly greater tongue volumes, tongue fat and percentage of tongue fat than obese controls without sleep apnea, after adjusting for potential confounders such as age, body mass index (BMI), gender and race.
Further analysis found that tongue fat percentage in participants with sleep apnea was site specific, with increased fat toward the base of the tongue in the retroglossal region.
"This is the first study to show that fat deposits are increased in the tongue of obese patients with obstructive sleep apnea," said principal investigator and senior author Dr Richard J Schwab, Professor in the Department of Medicine and co-director of the Penn Sleep Center at the University of Pennsylvania Medical Center in Philadelphia.
"Tongue size is one of the physical features that should be evaluated by a physician when screening obese patients to determine their risk for obstructive sleep apnea," said American Academy of Sleep Medicine President Dr Timothy Morgenthaler.
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Common warning signs for sleep apnea include snoring and choking, gasping, or silent breathing pauses during sleep.
The study involved 90 obese adults with sleep apnea and 31 obese controls without sleep apnea. All subjects underwent high resolution upper airway magnetic resonance imaging (MRI).
The researchers proposed that in addition to enlarging the size of the tongue, increased tongue fat may impair the functioning of the muscles that attach the tongue to bone, preventing these muscles from positioning the tongue away from the airway.
According to the researchers, future studies should examine the effectiveness of removing tongue fat through weight loss, upper airway exercises or surgery as a potential treatment for sleep apnea.
The results are published in the journal Sleep.