Weight loss is an effective treatment for obstructive sleep apnea (OSA), but scientists now believe this may be due to the fat dropping off an unexpected body part – the tongue.
Researchers used magnetic resonance imaging (MRI) to measure how weight loss impacts the upper airway in obese patients.
They found that reducing tongue fat is a primary factor in decreasing the severity of OSA.
The findings from the team at the Perelman School of Medicine at the University of Pennsylvania are published in the American Journal of Respiratory and Critical Care Medicine.
Dr Richard Schwab, chief of sleep medicine, said: “Most clinicians, and even experts in the sleep apnea world, have not typically focused on fat in the tongue for treating sleep apnea.
“Now that we know tongue fat is a risk factor and that sleep apnea improves when tongue fat is reduced, we have established a unique therapeutic target that we’ve never had before.”
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The condition involves breathing repeatedly stopping and starting, causing patients to wake up randomly throughout their sleep cycles.
It is usually marked by loud snoring and can increase the risk for high blood pressure and stroke.
While obesity is the primary risk factor for developing sleep apnea, there are other causes, such as having large tonsils or a recessed jaw.
The new study included 67 participants with mild to severe OSA who were obese with a body mass index greater than 30.
The patients lost almost 10 per cent of their body weight through diet or weight-loss surgery, on average, over six months.
Overall their sleep apnea scores improved by 31 per cent after the weight-loss intervention, as measured by a sleep study.
MRI scans were conducted before and after the weight-loss intervention on the pharynx and abdomen of the participant.
Using statistical analysis, researchers quantified changes between overall weight loss and reductions to the volumes of the upper airway structures to determine which structures led to the improvement in sleep apnea.
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The team found that a reduction in tongue fat volume was the primary link between weight loss and sleep apnea improvement.
According to the study, the weight loss also resulted in reduction of the pterygoid – a jaw muscle that controls chewing, and pharyngeal lateral wall – muscles on the sides of the airway.
Both these changes also improved sleep apnea, but not to the same extent as the reduction in tongue fat, the scientists say.
They believe tongue fat is a potential new therapeutic target for improving sleep apnea.
