Brain Amygdala Volume Increases in Veterans and Active-Duty Military Personnel With Combat-Related Posttraumatic Stress Disorder and Mild Traumatic Brain Injury.
Joel Pieper, Douglas G Chang, Sarah Z Mahasin and 9 others
PMID 31033749WHAT IT FOUND
Veterans and active-duty personnel with both mild traumatic brain injury and PTSD had amygdala volumes 6% larger than those with brain injury alone, but only after adjusting for head size.
Without this adjustment, no difference was found.
Key findings
01After normalizing for intracranial volume, the group with both mild traumatic brain injury and PTSD had 6% larger amygdala volumes than the group with mild traumatic brain injury only.
02When amygdala volumes were not normalized for head size, there was no significant difference between the two groups.
03The study did not find significant group differences in the volumes of the caudate, hippocampus, or anterior cingulate cortex.
STILL TO COME
How it was doneWhat they found
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What it does not show
The sample consisted almost entirely of males, so findings may not apply to female service members. The study lacked a healthy control group without brain injury or PTSD, making it difficult to determine if the amygdala changes are due to PTSD, the combination of conditions, or other factors. PTSD diagnosis methods varied; 36% of participants were diagnosed via clinical interview rather than standardized questionnaires like the CAPS or PCL. The study design was retrospective and cross-sectional, so it cannot determine if larger amygdala volumes cause PTSD or result from it.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not interpret the 6% increase in amygdala volume as a universal biological marker for PTSD. This difference was only statistically significant after adjusting for head size (intracranial volume), and the study did not include a healthy control group to compare against.