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Abstract

There is growing evidence that obesity is associated with brain Inflammation contributing to the pathogenesis of obesity. In humans, it is challenging to detect brain inflammation in vivo. Recently, quantitative magnetic resonance imaging (qMRI) has emerged as a tool to characterize pathophysiological processes in the brain with reliable and reproducible measures. Proton density imaging provides quantitative assessment of the brain water content, which is affected in different pathologies including inflammation. We enrolled 60 normal weight, overweight and obese men and women (body mass index (BMI) range 20.1-34.4 kg/m2 , age range 20-71 years, 73.3% men) to acquire water content mapping in vivo using MRI at 3 Tesla. We investigated potential associations between anthropometric measures of obesity with brain water content. No global changes in water content were observed with measures of obesity. However, the limbic lobe, midbrain and pons showed higher water content values with increasing BMI independent of age (p<0.005). Moreover, hypothalamic water content values revealed a strong relationship with BMI, especially in older adults. We identified the highest hypothalamic water content values in individuals fulfilling the definition for metabolic syndrome (p<0.005, adjusted for age). Using qMRI, we were able to detect marked water content changes in young and older obese adults. This is most likely due to chronic low-grade inflammation. Whether brain inflammation is a cause or consequence of obesity, in humans, stills needs to be investigated using a longitudinal study design.