Flashbacks -- the re-living of past experiences -- and/or recurring nightmares, anger or hyper-vigilance mark the disorder that can follow any psychologically traumatic event.
Researchers at the University of Minnesota in Minneapolis used a non-invasive measurement of the brain's magnetic fields called magnetoencephalography to identify flashbacks linked to a hyperactive brain network.
The researchers found differences between signals in the temporal and parieto-occipital right hemispheric areas of the brain that other types of brain scans -- such as X-ray or magnetic resonance imaging -- have not shown. In those with PTSD, the temporal cortex is thought to be responsible for the re-living of past experience, the researchers say.
The study, published in the Journal of Neural Engineering, finds a clear difference in activity among the circuitry in the brains of PTSD sufferers versus those without the condition.
"Having a diagnostic exam capable of confirming post-traumatic stress disorder is critical in treating these patients properly," Dr. Apostolos Georgopoulos, the study leader, said in a statement.