Published: 01-12-2015 10:45 | Updated: 01-12-2015 10:48

PTSD reveals imbalance between signalling systems in the brain

Experiencing a traumatic event can cause life-long anxiety problems, called posttraumatic stress disorder. Researchers from Uppsala University and Karolinska Institutet now show that people with posttraumatic stress disorder, PTSD, have an imbalance between two neurochemical systems in the brain, serotonin and substance P. The greater the imbalance, the more serious the symptoms patients have.

Many people experience traumatic events in life, e.g. robbery, warfare, a serious accident or sexual assault. Approximately 10 percent of people subjected to trauma suffer long-lasting symptoms in the form of disturbing flashbacks, insomnia, hyperarousal and anxiety. If these problems lead to impairment, the person is said to suffer from PTSD.

It has previously been shown that people with PTSD have altered brain anatomy and function. The current study, which is being published in the journal Molecular Psychiatry, shows that shows that people with PTSD have an imbalance between two neurochemical signalling systems of the brain, serotonin and substance P. By using a PET scanner, researchers were able to measure the relationship between these systems.

Design improved treatments

The study also shows that it is the imbalance between the two signalling systems which determines the severity of the symptoms suffered by the individual rather than the degree of change in a single system. Others have previously speculated that the biological basis of psychiatric disorders such as PTSD includes a shift in the balance between different signalling systems in the brain but none has yet proved it. According to the research team, the study results are a great leap forward in our understanding of PTSD. It will contribute new knowledge which can be used to design improved treatments for traumatised individuals.

The study was supervised by Mats Fredrikson, affiliated to both the Department of Psychology at Uppsala University and the Department of Clinical Neuroscience at Karolinska Institutet. The project was supported financially by the Swedish Research Council; the Swedish Brain Foundation; Riksbankens Jubileumsfond—the Swedish Foundation for Humanities and Social Sciences; and the Swedish Research Council for Health, Working Life and Welfare.


Overlapping expression of serotonin transporters and neurokinin-1 receptors in posttraumatic stress disorder: a multi-tracer PET study
Frick, A., Åhs, F., Michelgård Palmquist, Å., Pissiota, A., Wallenquist, U., Fernandez, M., Jonasson, M., Appel, L., Frans, Ö., Lubberink, M., Furmark, T., von Knorring, L., Fredrikson, M.
Molecular Psychiatry advance online publication 1 December 2015; doi: 10.1038/mp.2015.180