Nonalcoholic Fatty Liver Disease and Measures of Early Brain Health in Middle Aged Adults: The CARDIA study

OBJECTIVE: To assess associations between nonalcoholic fatty liver disease (NAFLD) and measures of brain health in a population-based sample of adults. METHODS: Participants from the CARDIA study (Y25 exam; age 43–55 years) with concurrent CT quantification of liver fat, visceral adipose tissue (VAT) and brain magnetic resonance (MR) images were included (n=505). NAFLD was identified after exclusion of other causes of liver fat. Total tissue volume (TTV) and gray matter cerebral blood flow (GM-CBF) were estimated using 3T brain MR images. RESULTS: NAFLD prevalence was 18%. NAFLD was associated with lower TTV and GM-CBF after adjusting for intracranial volume, demographics, and health behaviors (p<0.04 for all). In models with additional adjustment for cardiovascular risk factors the association of NAFLD with GM-CBF remained significant (p=0.04), but was attenuated after adjustment for VAT (p=0.06), and eliminated with BMI (p=0.20). NAFLD was not associated with TTV after adjustment for cardiovascular risk factors (p=0.10), or additional adjustment for VAT (p=0.14) or BMI (p=0.05). CONCLUSIONS: NAFLD is negatively associated with early brain health as assessed by MR measures of structure (TTV) and perfusion (GM-CBF). BMI and VAT attenuated this relationship providing insight into the potential metabolic role of liver fat in brain health and disease.