An Investigation of the Correlation Between Total Intracranial Volume and Body Mass Index

\looseness-1 Objective: Total intracranial volume (TICV) is an important covariate in brain volumetric analysis that can vary significantly between participants. This study aimed to investigate the association between body mass index (BMI) and TICV. Methods: 152 healthy volunteers were recruited. The BMI was calculated, and T1-weighted images were acquired to estimate brain volumetric values. The data were analyzed using volBrain software. Results: Male participants have significantly higher GM, WM, CSF, TICV, cerebellum GM, cortical GM, subcortical GM and cerebrum GM volumes compared to female. There were significant differences in GM, TICV, cerebellum GM, cortical GM, subcortical GM and cerebrum GM volumes between BMI subgroups. Dunn-Bonferroni tests revealed that participants with a normal BMI had significantly higher volumes of GM, TICV, cerebellum GM, cortical GM and cerebrum GM compared to individuals with overweight and obese. In addition, subcortical GM volume was significantly higher in participants with normal BMI compared to individuals with obesity. Pearson's correlation analysis revealed that age and BMI are significantly negatively correlated with GM, cerebellum GM, cortical GM, subcortical GM and cerebrum GM. Moreover, BMI was found to be significantly negatively correlated with TICV. The GLM analysis revealed that the association between age, biological sex and BMI had a significant influence on TICV. Conclusion: Brain volumetric measurements were found to be influenced by age, biological sex and BMI and need to be regressed out from volumetric analysis.