HOW DO PEOPLE GET NASH?
NASH is multi-factorial.
There is no single cause for NASH. The disease is modulated by a complex interplay of metabolic, genetic, internal and external environmental factors.
NASH is widely considered to be the liver expression of the metabolic syndrome, that is, diseases related to diabetes mellitus type 2, insulin resistance, central obesity, hyperlipidemia, and hypertension.
There is already a worldwide epidemic of diabetes and obesity and the figure shows the expected increases of diabetes in different parts of the world, which will closely correlate with rates of NASH.
NASH affects about 10% of people in the developed world. It is the most common non-communicable liver disease, affecting about 2-5% of the US population and has a similar prevalence in China and Europe. Up to 25% of the adults with NASH may have advanced to NASH-related cirrhosis.
NASH affects individuals of all age demographics. The disease affects adults 40-65 years of age and it is more common in women than in men. Interestingly, children 2-17 years of age can also be affected with NASH. Non-Alcoholic Fatty Liver Disease [NAFLD], which is the precursor to NASH, is more common in young boys than girls. Almost 90% of children with NASH are obese and many are insulin resistant.
NAFLD is suspected in patients with diabetes, obesity or dyslipidemia who do not drink alcohol excessively. Since patients are asymptomatic during the early stages of NAFLD, it is usually detected incidentally during testing for other conditions. Elevated levels of liver enzymes alanine-transaminase [ALT] and aspartate transaminase [AST] in the blood are common indicators of NASH.
Steatosis in the liver can be confirmed by various imaging techniques, including MRI, MRS, ultrasound and computed tomography. However, these imaging techniques are unable to determine the stage of fibrosis accurately. Transient elastography [Fibroscan], is the only method that no invasively, can accurately determine the stage of liver fibrosis. By measuring the velocity of the sound waves passing through the liver, tissue stiffness (a property of the extracellular matrix correlated with fibrosis), is measured.
Finally, liver biopsy remains the gold standard for identifying NASH in the liver. This procedure includes taking a small piece of the liver from the patient. Subsequently, the tissue is processed and histologically graded by pathologists. Some of the drawbacks of this method include pain and tissue complications associated with the procedure. Overall, there is a pressing need to develop non-invasive diagnostic tools for NASH, like DeMILI.
The current standard of care for NASH patients comprises of lifestyle changes, such as sustained weight loss, diet, exercise or bariatric surgery and the management of related diseases, diabetes and hyperlipidemia. There are no approved pharmacological treatments for NASH.