Objective: Obesity has been related to structural brain abnormalities. Increasing evidence suggests that accumulation of fat in the liver is an important determinant of cardiometabolic complications of obesity. The purpose of this study was to investigate the association between CT-assessed liver-to-spleen attenuation ratio as a measure of liver steatosis and MRI-assessed brain tissue integrity in middle-aged to elderly persons.
Subjects and methods: CT and MRI were performed on 213 participants (114 women, 99 men; mean age, 65 ± 7 years). Brain tissue integrity was assessed by magnetization transfer imaging. Linear regression analysis was adjusted for age, sex, vascular risk factors, and total body fat estimated from bioelectrical impedance analysis.
Results: Seventy-nine participants had normal weight (body mass index [BMI], 18.5-24.9), and 134 were overweight (BMI ≥ 25). Significant interaction was found between liver-to-spleen ratio and BMI (p = 0.001). In the overweight group, liver fat was associated with reduced brain tissue integrity in both gray matter (standardized β = 0.22; 95% CI, 0.07-0.36) and white matter (standardized β = 0.31; 95% CI, 0.15-0.45). These associations were not found in the normal weight group (gray matter standardized β = -0.08; 95% CI, -0.33 to 0.16; white matter standardized β = -0.09; 95% CI, -0.36-0.14).
Conclusion: The results indicate that liver fat assessed with CT relates to MRI markers of incipient brain injury in middle-aged to elderly overweight persons.
Keywords: body fat distribution; brain MRI; liver fat; obesity.