Glymphatic alteration in NAFLD patient: a preliminary magnetic resonance imaging study based on DTI-ALPS.

OBJECTIVE: This study aims to investigate alterations in glymphatic system (GS) function in patients with non-alcoholic fatty liver disease (NAFLD) and explore the relationship of these alterations with cognition and clinical indicators. MATERIALS AND METHODS: In this cross-sectional study, forty-three patients with pre-cirrhotic NAFLD (male: 37, mean age: 38.2 ± 6.7 years) and twenty-three age-, sex-, and education-matched controls (male: 17, mean age: 41.0 ± 6.7 years) underwent diffusion tensor imaging (DTI) examination and cognitive measurements. The DTI analysis along the perivascular space (DTI-ALPS) index, calculated from the DTI data, assessed differences in GS function between the two groups. Linear regression analysis examined the relationship between the ALPS index and Z-transformed cognitive scores. Spearman/Pearson correlation analysis was conducted for assessing the relationship of the ALPS index with clinical indicators. RESULTS: After adjusted for age, sex, and BMI, NAFLD patients exhibited significantly lower ALPS index and higher diffusivity of projection fibers in the direction of the y-axis than controls (both P < 0.001). In the NAFLD group, the ALPS index was significantly correlated with the Mini-Mental State Examination score (beta [95% CI] = 2.123 [0.156, 4.091], P = 0.035) and the clock drawing score (beta [95% CI] = 4.233 [0.073, 8.393], P = 0.046) after adjusting for age, sex, body mass index, and education level. In addition, there was a significantly positive correlation between the ALPS index and abdominal visceral adipose tissue area (r = 0.353, P = 0.020) after adjusting for age, sex, and BMI in NAFLD patients. CONCLUSION: NAFLD patients without cirrhosis showed significantly a reduced ALPS index compare to matched controls, indicating potential alterations in GS function. These alterations correlated with cognitive performance and clinical indicators, implying a possible link between GS function and cognitive performance in NAFLD that requires longitudinal validation.