Cognitive Deficits Linked to Nonalcoholic Liver Disease

Nancy A. Melville

November 11, 2014

BALTIMORE, Maryland — Patients with nonalcoholic fatty liver disease (NAFLD) show deficits in cognitive function even in the absence of cardiovascular disease risk factors, a new study suggests.

The study of 5662 adults with moderate to severe hepatic steatosis showed that, in addition to its association with the cardiovascular risk factors that have been linked with cognitive impairment, NAFLD is also independently associated with the deficits.

"To our knowledge, this may be the first study to systematically examine the association between NAFLD and cognitive impairment in a large US representative population," lead author Mariana Lazo, MD, PhD, an assistant professor of medicine and epidemiology with Johns Hopkins University, Baltimore, Maryland, told Medscape Medical News.

The results were presented at the recent American Neurological Association (ANA) 2014 Annual Meeting.

The patients evaluated were enrolled in the Third National Health and Nutritional Examination Survey (NHANES III). All patients were administered three cognitive function tests: the Simple Reaction Time Test (SRTT), the Symbol Digit Substitution Test (SDST), and the Serial Digit Learning Test (SDLT).

After adjusting for factors including age, sex, race, body mass index, waist circumference, hypertension, diabetes, hypercholesterolemia, acute myocardial infarction, and stroke, the researchers found NAFLD to be associated with worse cognitive performance on the SRTT test (P = .011), the SDST (P = .039), and the SDLT (P < .001).

Additionally, patients with NAFLD showed associations between cognitive test results on the SDLD and liver enzymes, including alanine aminotransferase (P = .020) and aspartate aminotransferase (P = .026).

No association was seen between liver enzymes and cognitive function among patients without NAFLD.

Considering the high prevalence of fatty liver disease, the implications of poorer cognitive function is significant, Dr Lazo noted.

"NAFLD is one of the most common chronic conditions in the US and in other western countries, with a prevalence of 20%-30% higher that diabetes, [and] it is in fact associated with the development of diabetes," she said.

The specific mechanisms that might underlie cognitive deficits associated with the disease are uncertain, but the common culprit of inflammation may play a role, Dr Lazo suggested.

"Currently the mechanisms by which fatty liver may be associated with cognitive decline are unclear. However, one potential pathway may be related with the pivotal role of the liver for the metabolism of many substances — and the subclinical inflammation that may therefore be present in the body."

There was no outside funding for the study. Dr Lazo has disclosed no relevant financial relationships.

American Neurological Association (ANA) 2014 Annual Meeting. Abstract M1323. Presented October 13, 2014.

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