Right now, it is difficult for clinicians to make a diagnosis between PTSD and mild traumatic brain injury (MTBI) since patients experience similar symptoms and the conditions are unable to be detected by normal structural neuroimaging. However, using hybrid imaging with positron emission tomography and computed tomography (PET/CT), researchers are able to differentiate between the two conditions.
Researchers looked at the HPA axis, comprised of the adrenal glands above each kidney, the hypothalamus, and pituitary gland, which regulates many body processes. “The HPA axis is a complex system with a feedback loop, so that damage to any one of the three areas will affect the others,” said study lead author Thomas M. Malone, B.A., from the Department of Neurosurgery at Saint Louis University School of Medicine in Saint Louis. “It’s suspected of playing an important role in PTSD, but there is limited neuroimaging research in the veteran population.”
For the study, researchers reviewed 159 brain 18F-FDG PET/CT exam records, which focuses on metabolism by measuring uptake of the radiopharmaceutical FDG, and found FDG uptake in the hypothalamus was significantly lower in the MTBI-only group. The FDG uptake in the pituitary gland was significantly higher in the MTBI and PTSD group.
“This study sheds light on the complex issue of PTSD, which also has symptom overlap with depression and anxiety,” Malone said. “Our findings reinforce the theory that there is something physically and biologically different in veterans who have MTBI and PTSD compared to those who just have MTBI.”