Intracranial Volume & Casualties of Combat-related mTBI & PTSD

Research Paper Title

Brain Amygdala Volume Increases in Veterans and Active-Duty Military Personnel With Combat-Related Posttraumatic Stress Disorder and Mild Traumatic Brain Injury.

Background

To identify amygdalar volumetric differences associated with posttraumatic stress disorder (PTSD) in individuals with comorbid mild traumatic brain injury (mTBI) compared with those with mTBI-only and to examine the effects of intracranial volume (ICV) on amygdala volumetric measures.

Marine Corps Base and VA Healthcare System.

A cohort of veterans and active-duty military personnel with combat-related mTBI (N = 89).

Methods

Twenty-nine participants were identified with comorbid PTSD and mTBI. The remaining 60 formed the mTBI-only control group.

Structural images of brains were obtained with a 1.5-T MRI scanner using a T1-weighted 3D-IR-FSPGR pulse sequence. Automatic segmentation was performed in Freesurfer.

Amygdala volumes with/without normalisations to ICV.

Results

The comorbid mTBI/PTSD group had significantly larger amygdala volumes, when normalised to ICV, compared with the mTBI-only group.

The right and left amygdala volumes after normalisation to ICV were 0.122% ± 0.012% and 0.118% ± 0.011%, respectively, in the comorbid group compared with 0.115% ± 0.012% and 0.112% ± 0.009%, respectively, in the mTBI-only group (corrected P < .05).

Conclusions

The ICV normalisation analysis performed here may resolve previous literature discrepancies.

This is an intriguing structural finding, given the role of the amygdala in the challenging neuroemotive symptoms witnessed in casualties of combat-related mTBI and PTSD.

Reference

Pieper, J., Chang, D.G., Mahasin, S.Z., Swan, A.R., Quinto, A.A., Nichols, S.L., Diwakar, M., Huang, C., Swan, J., Lee, R.R., Baker, D.G. & Huang, M. (2020) Brain Amygdala Volume Increases in Veterans and Active-Duty Military Personnel With Combat-Related Posttraumatic Stress Disorder and Mild Traumatic Brain Injury. The Journal of Head Trauma Rehabilitation. 35(1):E1-E9. doi: 10.1097/HTR.0000000000000492.

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