Researchers set out to study patients with post-traumatic stress disorder (PTSD) using PET scans. They found that a greater imbalance between two neurochemical systems in the brain—serotonin and substance P—meant individuals were more likely to experience PTSD symptoms.

The research team from Uppsala University and Karolinska Institutet in Stockholm published their study in Molecular Psychiatry.

Using PET imaging, researchers examined the serotonin and substance P systems individually, as well as their overlapping expression in 16 patients with PTSD and 16 healthy controls.

“Patients, relative to controls, displayed lower degree of overlapping expression between SERT and NK1 receptors in the putamen, thalamus, insula and lateral orbitofrontal gyrus, lower overlap being associated with higher PTSD symptom severity,” wrote the authors. “Expression overlap also explained more of the symptomatology than did either system individually, underscoring the importance of taking interactions between the neurochemical systems into account.”

With this information, researchers are now able to grasp a better understanding and treat patients suffering from PTSD.  

“Our results suggest that aberrant serotonergic-SP/NK1 couplings contribute to the pathophysiology of PTSD and, consequently, that normalization of these couplings may be therapeutically important,” the authors noted.