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 Researchers found that among obese adolescents with NAFLD, those
with the most severe liver disease also had the most severe sleep
disordered breathing that caused them to experience periods of low
oxygen at night.
“This really focuses on the role of oxidative stress both
systemically and specifically in the liver as a driving factor of
fibrosis and liver disease getting worse,” said lead investigator
Dr. Shikha Sundaram of the Children's Hospital Colorado and the
University of Colorado School of Medicine.
Sleep apnea also increases the risk of cardiovascular disease,
putting extra pressure on the heart to get oxygenated blood to the
body, Sundaram told Reuters Health.
“Now we know that it also impacts the liver,” as periods of normal
oxygen levels and low oxygen levels repeat during sleep and increase
scar tissue, though the mechanism is not yet completely understood,
she said.
About seven million children in the U.S. have NAFLD, which can cause
scarring in the liver and can lead to liver failure and the need for
a transplant. NAFLD is also a major risk factor for type 2 diabetes.
The condition may be related to genetics, obesity and some
medications, and it can be treated but not cured.
Obstructive sleep apnea, when a sleeper’s airway collapses and
breathing stops then restarts abruptly, is common with obesity. The
repeated interruptions in breathing throughout the night cause low
blood oxygen levels, known as hypoxia, and have been linked to heart
disease and stroke.
Past research has also tied sleep apnea to worsening NAFLD in
adults, the study team notes in Journal of Hepatology. To see if
this is true for teens, the researchers compared 36 obese teens with
NAFLD, all around age 13, who underwent sleep studies, liver testing
and urine analysis.
Of the 36 teens with NAFLD, 25 had sleep apnea or periods of
hypoxia, during sleep.
Teens with obstructive sleep apnea/hypoxia had more severe liver
fibrosis - scar tissue - than others, and had higher markers of
oxidative stress, which is associated with worsening NAFLD, the
researchers write.
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The 23 teens with definite nonalcoholic steatohepatitis (NASH), a
more severe form of liver disease that carries the highest risk for
cirrhosis, end stage liver disease and liver cancer, had greater
oxidative stress at night than those without NASH.
This and other recent studies indicate that liver disease and sleep
apnea are closely related, Sundaram said. Both are related to
obesity.
“I think that this and our previous work really is suggesting that
if you have one or the other disease, talk to your physician, there
is a possibility that you have the other disease,” she said.
Untreated, sleep apnea can make fatty liver disease worse, she said.
If your child has NAFLD, ask your provider about the possibility of
sleep apnea screening, she added.
Future trials should explore whether treating sleep apnea with a
continuous positive airway pressure (CPAP) machine may affect NAFLD
progression for teens, according to Maurizio Parola of the
University of Torino Italy and Dr. Pietro Vajro of the University of
Salerno in Italy, who coauthored an editorial on the findings.
SOURCE: http://bit.ly/2aP6SvB and http://bit.ly/2aOCzcE Journal of
Hepatology, online August 5, 2016.
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