A Blood-Based Lipid Profile Associated With Hippocampal Volume and Brain Resting-State Activation Within Obese Adults...

Obesity and dyslipidemia may be associated with hippocampal alterations and may increase the risk of neurodegeneration. This study studied hippocampal anatomical and functional association with a lipid profile based on high-density lipoprotein, low-density lipoprotein, and triglyceride related to dyslipidemia in obese and nonobese adults. A whole-brain analysis was also conducted to examine the effect of dyslipidemia on resting-state function across the brain. In total, 553 UK Biobank participants comprised three groups based on body mass index (BMI) rankings: obese adults with high BMI (O_High, n = 184, 32.7 kg/m² ≤ BMI ≤53.4 kg/m²), obese adults with a lower BMI (O_Low, n = 182, 30.3 kg/m² ≤ BMI ≤32.6 kg/m²), and nonobese controls (n = 187). Structural MRI and functional MRI data were accessed. The fractional amplitude of low-frequency fluctuations (fALFFs) maps was calculated to reflect resting-state brain activity. A lipid health factor was created using principal component analysis. Linear models tested for associations between the lipid health score and hippocampal MRI readouts. With a higher lipid health factor corresponding to a lower dyslipidemia risk, we found a positive correlation between hippocampal volume with the lipid health factor exclusively in group O_Low (p = 0.01). We also found a positive association between the lipid health factor and hippocampal fALFF in group O_High (p = 0.02). Additional fALFF voxel-wise analysis to group O_High also implicated that the premotor cortex, amygdala, thalamus, subcallosal cortex, temporal fusiform cortex, and middle temporal gyrus brain regions are related with lipid. The study finds novel associations among circulating lipid, hippocampal structure, and hippocampal function exclusively in the obese adults.