Favorable impact of non-alcoholic fatty liver disease on the cerebral white matter hyperintensity in a neurologically healthy population

Background and purpose Although non-alcoholic fatty liver disease (NAFLD) shares common cardiovascular risk factors with cerebral white matter hyperintensity (WMH), few studies have reported the association between NAFLD and WMH. The association between the presence of NAFLD with its severity and the volume of WMH was investigated. Methods This cross-sectional study was conducted for 2460 subjects who voluntarily participated in health screening check-ups including brain magnetic resonance imaging and liver ultrasonography at the Health Promotion Center at Seoul National University Hospital from 2009 to 2013. Ultrasonography was used to detect the presence and severity of NAFLD combined with the NAFLD fibrosis score and the FIB-4 index. The volume of WMH was measured using a semi-automated quantification method by a trained neurologist. Results The prevalence of NAFLD was 36.5%, and the median volume of WMH in all the subjects was 1.1 ml (interquartile range 0.2-2.7 ml). The presence of NAFLD was associated with a smaller volume of WMH [β (standard error, SE) -0.051 (0.046); P = 0.012]. Moderate to severe NAFLD was associated with a smaller volume of WMH than was non-NAFLD [β (SE) -0.067 (0.061); P = 0.002]. The negative correlation observed between NAFLD severity and WMH volume was persistent only in those with low FIB-4 index and low NAFLD fibrosis scores, whereas there was a positive association in those with high FIB-4 index and NAFLD fibrosis scores. Conclusions Non-alcoholic fatty liver disease, and its severity, showed a favorable association with WMH volume. However, its causality and mechanism should be evaluated in further relevantly designed studies.