Suspected non-alcoholic fatty liver disease (NAFLD) is increasing in teens, affecting approximately 10 percent of the age group. Historically seen more often in adults, NAFLD can lead to liver damage, diabetes, hypertension and cancer.
In a study funded by the National Institutes of Health (NIH), researchers led by Miriam Vos, MD, MSPH, assistant professor of pediatrics at Emory University School of Medicine and a pediatric hepatologist at Children’s Healthcare of Atlanta, sought to determine whether rates of NAFLD seem high because people are studying them more closely or whether there really are more cases of teenagers with NAFLD.
The study was presented at Digestive Disease Week, an annual conference jointly sponsored by the American Association for the Study of Liver Diseases, the American Gastroenterological Association Institute, the American Society for Gastrointestinal Endoscopy and the Society for Surgery of the Alimentary Tract.
Investigators reviewed nationally representative data of more than 10,000 12- to 18-year-olds from the National Health and Examination Survey datasets, spanning 1988 to 2008. Suspected NAFLD was defined as overweight/obese (those with a body mass index greater than the 85th percentile) with elevated alanine aminotransferase (ALT), a blood test that is typically used to detect liver injury.
According to the study, the prevalence of NAFLD among U.S. teens grew from 3.6 percent to 9.9 percent, increasing at a rate faster than teen obesity during the same time. In looking at cross-sectional data to explain the increase in prevalence of NAFLD, researchers found a link to increased NAFLD and waist circumference — the measure of the distance around the abdomen half way between the inferior margin in the last rib and the crest of the hip bone.
“We know that if a child is overweight, they are more likely to be overweight as an adult,” says Vos. “We know from national data that teens with fatty liver disease become adults with fatty liver disease, unless they improve their diet and lose a significant amount of weight.”
Vos noted that early intervention for NAFLD is essential, as is a coordinated plan of lifestyle modification and in some cases, medication.
“Adolescents may have an easier time losing weight compared to adults because they have been overweight for a shorter period of time, so there is less resistance to improving lifestyle habits like diet and exercise,” says Vos. “My hope for the future is that we will have medications to help treat the most severe cases of NAFLD to help complement a healthy regimen of diet and physical activity.”
This summer, the -NIH-sponsored NASH Clinical Research Network will start a new clinical trial to research the treatment of NAFLD.
In the past, Vos and colleagues have studied the connection between diet and fat in the liver and increased cardiovascular risk. Data shows that cardiovascular disease is prevalent in adults with NAFLD, and multiple studies have shown that adolescents with NAFLD have markers that show increased risk for cardiovascular disease.