Nonalcoholic fatty liver disease, serum cytokines, and dementia among rural‐dwelling older adults in China: A population‐based study

Little is known about whether nonalcoholic fatty liver disease (NAFLD) is associated with dementia or the role of serum proinflammatory cytokines in the association. We aimed to investigate the interrelationships of NAFLD, serum cytokines, and dementia among rural-dwelling older adults.This population-based cross-sectional study included 5129 participants (aged ≥60 years; 61.79% women) who were living in rural communities and examined in March 2018-September 2018. NAFLD was defined through transabdominal ultrasound examination in the absence of hepatitis B or excessive alcohol consumption. Serum cytokines were measured in a subsample (n = 1686). Dementia, Alzheimer disease (AD), and vascular dementia (VaD) were diagnosed following international criteria. Data were analyzed with logistic regression and mediation models.Of the 5129 participants, 455 (8.87%) were detected with moderate-to-severe NAFLD, and 292 (5.69%) were diagnosed with dementia (188 with AD and 96 with VaD). The multivariable adjusted odds ratios associated with moderate-to-severe (vs. no-to-mild) NAFLD were 2.22 (95% confidence interval [CI] = 1.41-3.49) for all-cause dementia, 1.88 (95% CI = 1.01-3.50) for AD, and 2.62 (95% CI = 1.33-5.17) for VaD. In the cytokine subsample, controlling for multiple potential confounders, moderate-to-severe NAFLD was significantly associated with higher levels of serum monocyte chemotactic protein-1, interleukin-17A, interleukin-6 (IL-6), interleukin-8, and tumor necrosis factor-α (P < 0.05). The mediation analysis showed that IL-6 mediated 12.56% of the association between NAFLD and VaD.Moderate-to-severe nonalcoholic fatty liver disease is associated with dementia and AD, especially with VaD, among rural-dwelling Chinese older adults, in which the association with VaD is partly mediated by serum inflammatory cytokines.