A meta-analysis of studies reporting brain activity in individuals with a diagnosis of PTSD has revealed differences between the brain activity of individuals with PTSD and that of groups of both trauma-exposed (those who had experienced trauma but didn't have a diagnosis of PTSD) and trauma-naïve (those who hadn't experienced trauma) participants.
The critical difference between those who developed PTSD and those who experienced trauma but didn't develop PTSD lay in the basal ganglia. Specifically:
- PTSD brains compared with trauma-exposed controls showed differentially active regions of the basal ganglia
- trauma-exposed brains compared with trauma-naïve controls revealed differences in the right anterior insula, precuneus, cingulate and orbitofrontal cortices, all known to be involved in emotional regulation
- PTSD brains compared with both control groups showed differences in activity in the amygdala and parahippocampal cortex.
The finding is consistent with other new evidence from the researchers, that other neuropsychiatric disorders were also associated with specific imbalances in specific brain networks.
The findings suggest that, while people who have experienced trauma may not meet the threshold for a diagnosis of PTSD, they may have similar changes within the brain, which might make them more vulnerable to PTSD if they experience a subsequent trauma.
The finding also suggests a different perspective on PTSD — that it “may not actually be abnormal or a 'disorder' but the brain's natural reaction to events and experiences that are abnormal”.
 . Post-traumatic stress influences the brain even in the absence of symptoms: A systematic, quantitative meta-analysis of neuroimaging studies. Neuroscience & Biobehavioral Reviews [Internet]. 2015 ;56:207 - 221. Available from: http://www.sciencedirect.com/science/article/pii/S014976341500192X