The normalizing properties of intracranial volume across race and sex
Published in Brain Communications, 2025
Recommended citation: Liu, P., Zemlyanker, D., Gopinath, K., Cheng, Y., He, Y., Izquierdo-Garcia, D., Gomez-Isla, T., Das, S., Nasr, S., Sheth, K. N., Rosen, M. S., Kimberly, W. T., de Havenon, A., Shen, F. X., & Iglesias, J. E. (2025). The normalizing properties of intracranial volume across race and sex. Brain Communications, 7(4), fcaf271. https://doi.org/10.1093/braincomms/fcaf271
We analyzed 5,977 subjects from three racial groups to examine how intracranial volume (ICV) normalization affects brain measurements across demographic groups. The research compared sex- and race-specific aging trajectories in brain regions both before and after ICV correction, using statistical measures of effect size to evaluate the impact of normalization. We demonstrate two central findings: (1) differences in intracranial volume across sex are consistent across race and vice versa, and (2) ICV normalization almost completely accounts for differences by race and sex in regional brain volumes. These findings support combining participants of different sexes and races in volumetric neuroimaging studies when researchers normalize brain region measurements to intracranial volume, effectively eliminating the confounding effects of head size differences across demographic groups.