Source: Thailand Medical News Jan 11, 2020 4 years, 3 months, 2 weeks, 1 day, 13 hours, 4 minutes ago
For a long time now, it has been found that losing weight is an effective treatment for Obstructive
Sleep Apnea (OSA), but why exactly this is the case has remained unclear. Now, researchers in the Perelman School of Medicine at the University of Pennsylvania have discovered that improvements in
sleep apnea symptoms appear to be linked to the reduction of
fat in one unexpected body part — the
tongue.
Utilizing magnetic resonance imaging (MRI) to measure the effect of weight loss on the upper airway in obese patients, researchers found that reducing
tongue fat is a primary factor in lessening the severity of
sleep apnea. The findings were published today (January 10, 2020) in the
American Journal of Respiratory and Critical Care Medicine.
Dr Richard Schwab, MD, Chief of Sleep Medicine told
Thailand Medical News, “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.”
More than two hundred million people globally suffer from
sleep apnea, a serious health condition in which breathing repeatedly stops and starts, causing patients to wake up randomly throughout their sleep cycles. The condition, which is usually marked by loud snoring, can increase your 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. CPAP (continuous positive airway pressure) machines improve
sleep apnea in about 75 percent of patients, studies suggest, but for the other 25 percent ie those who may have trouble tolerating the machine, alternative treatment options, such as oral appliances or upper airway surgery, are more complicated.
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CPAP MACHINES IMPROVE SLEEP APNEA IN ABOUT 75 PERCENT OF PATIENTS, STUDIE
S SUGGEST, BUT FOR THE OTHER 25 PERCENT — THOSE WHO MAY HAVE TROUBLE
TOLERATING THE MACHINE — ALTERNATIVE TREATMENT OPTIONS, SUCH AS ORAL
APPLIANCES OR UPPER AIRWAY SURGERY, ARE MORE COMPLICATED.
A research study in 2014 led by Dr Schwab compared obese patients with and without
sleep apnea, and found that the participants with the condition had significantly larger
tongues and a higher percentage of
tongue fat when compared to those without
sleep apnea. The researchers next step was to determine if red
ucing
tongue fat would improve symptoms and to further examine cause and effect.
The current study included 67 participants with mild to severe obstructive
sleep apnea who were obese ie those with a body mass index greater than 30.0. Through diet or weight loss surgery, the patients lost nearly 10 percent of their body weight, on average, over six months. Overall, the participants’
sleep apnea scores improved by 31 percent after the weight loss intervention, as measured by a sleep study.
The study participants underwent MRI scans to both their pharynx as well as their abdomens, before and after the weight loss intervention. Then, using a statistical analysis, the research team 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. The team found that a reduction in
tongue fat volume was the primary link between weight loss and
sleep apnea improvement.
The research also found that weight loss resulted in reduced pterygoid (a jaw muscle that controls chewing) and pharyngeal lateral wall (muscles on the sides of the airway) volumes. Both these changes also improved
sleep apnea, but not to the same extent as the reduction in
tongue fat.
The researchers believe that
tongue fat is a potential new therapeutic target for improving
sleep apnea. They suggest that future studies could be designed to explore whether certain low
-fat diets are better than others in reducing
tongue fat and whether cold therapies like those used to reduce stomach
fat, might be applied to reducing
tongue fat. However, Dr Schwab notes, these types of interventions have not yet been tested.
Dr Schwab’s team is also examining new interventions and other risk factors for
sleep apnea, including whether some patients who are not obese but who have “fatty”
tongues could be predisposed to
sleep apnea, but are less likely to be diagnosed.
A recent related study by Dr Schwab found that ethnicity may also play a role in
sleep apnea severity. His research team compared the upper airway anatomy of Chinese and Icelandic patients with
sleep apnea, and found that, compared to Icelandic patients of similar age, gender, and symptoms, Chinese patients had smaller airways and soft tissues, but bigger soft palate volume with more bone restrictions. This means that Asian patients may generally be more at risk for severe
sleep apnea symptoms. The bottom line, according to Schwab, is that all patients who suffer from snoring or sleepiness should be screened for
sleep apnea, whether or not they appear to fall into the typical “high-risk” obese categories.
Dr Schwab further commented to Thailand
Medical News, “Primary care doctors, and perhaps even dentists, should be asking about snoring and sleepiness in all patients, even those who have a normal body mass index, as, based on our data, they may also be at risk for
sleep apnea,”
Reference: “Effect of Weight Loss on Upper Airway Anatomy and the Apnea Hypopnea Index: The Importance of Tongue Fat” by Stephen H. Wang, Brendan T Keenan, Andrew Wiemken, Yinyin Zang, Bethany Staley, David B. Sarwer, Drew A. Torigian, Noel Williams, Allan I Pack and Richard J Schwab, 10 January 2020, American Journal of Respiratory and Critical Care Medicine.
DOI: 10.1164/rccm.201903-0692OC
