Nonalcoholic fatty liver disease and alcohol-related liver disease together constitute the majority of the burden of liver disease and cirrhosis globally. There has been increasing interest in the differentiation between these two entities over the past few years. However, it has been recognized that there exists a significant overlap between the two.

The key pathophysiological aspects are quite similar for the two conditions, except for the mechanisms directly related to alcohol. This acts as an additional factor in the presence of metabolic risk factors. Genetic factors associated with the two conditions have also been quite similar. Both the conditions are more prevalent in males, with the difference being more significant in the ALD group. This could be attributed to harmful alcohol consumption, seen more frequently in males. Of note, NAFLD advanced stages usually present in older age when compared with ALD.

In terms of laboratory features, AST/ALT ratio of <1 is more frequently noted in NAFLD than ALD, in the absence of cirrhosis. Histological findings are very similar in both the conditions. Some of the findings specific for ALD include alcoholic foamy degeneration or cholestasis, or fibroobliterative venous lesions.

Various drugs that are now included in clinical trials in NAFLD, could also be appraised in ALD, as similar mechanisms of action are at work in ALD.

The similarities in these two conditions outnumber the differences. There is a huge overlap between the risk factors. Therefore, use of a common designation such as Fatty Liver Disease (FLD) or Metabolic Fatty Liver disease (MEFLD) could be considered.

Source: Craciun A, Lackner C, Cortez-Pinto H. Nonalcoholic Fatty Liver Disease versus Alcohol-related Liver Disease: Is it Really so Different? Current Pharmaceutical Design 2020;26(10):1093-1109(17).