Dyslipidemia links obesity to early cerebral neurochemical alterations

OBJECTIVE: To examine the role of hypertension, hyperglycemia and dyslipidemia in potentially accounting for obesity-related brain vulnerability in the form of altered cerebral neurochemistry. DESIGN AND METHODS: Sixty-four adults, ages 40 to 60 years, underwent a health screen and proton magnetic resonance spectroscopy ((1)H MRS) of occipitoparietal grey matter to measure N-acetyl aspartate (NAA), choline (Cho), myo-inositol (mI) and glutamate (Glu) relative to creatine (Cr). The causal steps approach and non-parametric bootstrapping were utilized to assess if fasting glucose, mean arterial pressure or peripheral lipid/lipoprotein levels mediate the relationship between body mass index (BMI) and cerebral neurochemistry. RESULTS: Higher BMI was significantly related to higher mI/Cr, independent of age and sex. BMI was also significantly related to two of the proposed mediators, triglyceride and HDL-cholesterol, which were also independently related to increased mI/Cr. Finally, the relationship between BMI and mI/Cr, was significantly attenuated after inclusion of triglyceride and HDL-cholesterol into the model, one at a time, indicating statistical mediation. CONCLUSIONS: Higher triglyceride and lower HDL levels statistically account for the association between BMI and myo-inositol, pointing towards a potentially critical role for dyslipidemia in the development of cerebral neurochemical alterations in obesity.