Relationship between Body Mass Index, Gray Matter Volume and peripheral inflammation in patients with post-COVID condition

Background Obesity is linked to low-grade peripheral inflammation and is recognized as an independent risk factor for severe COVID-19. Obesity and overweight have furthermore been shown to relate to structural brain alterations. Post-COVID condition (PCC) has in turn been associated with structural brain alterations and lingering immunological changes. Therefore, in this study, we aimed to assess whether obesity contributes to structural brain alterations and differences in immunological markers in PCC patients. Methods We investigated a previously established cohort of PCC patients (n = 61). Whole-brain comparison of gray matter volume (GMV) was conducted by voxel-based morphometry (VBM). Obesity, as measured by body mass index (BMI), as well as age, gender and total intracranial volume (TIV) were included as regressors in a linear regression model. Results A significant negative association was found between higher BMI and lower GMV in the right thalamus (p(FWE) = 0.039, k = 209, TFCE = 1037.97, x = 18, y = −21, z = 8). Moreover, BMI, GMV and immunological markers were linked in PCC. Specifically, BMI was primarily positively associated with Interleukin-6 and negatively with Interleukin-7, while GMV showed strong positive associations with Interleukin-8. Limitations A small cohort size and no available data on BMI changes before and after SARS-CoV2 infection limit the interpretation of our findings. Conclusion The results suggest that BMI contributes to GMV alterations in PCC patients, with both BMI and GMV being associated with peripheral immunological markers. These findings indicate that converging mechanisms, such as inflammation and structural brain alterations, may play a role in obesity and PCC.