Structural differences in brain structure after trauma An analysis based on The Tromsø Study

Abstract

Research conducted on trauma patients has shown that the local brain regions in patients diagnosed with post-traumatic stress disorder (PTSD) is smaller than in people who are not diagnosed with PTSD. Therefore, the research question we address in this master thesis is: Are there structural brain differences in participants that have experienced traumatic incidents in their lives? We also use anxiety and depression as a mediating variable to distinguish whether brain-volume reductions associated with PTEs may be caused by depression/anxiety rather than the potentially traumatic incidents themselves. We have analyzed data from the Tromsø Study and studied a sub-sample of 1864 participants (age span 40-87 years) that underwent magnetic resonance imaging (MRI). We used structural equational model (SEM) with a sum-score of childhood PTEs and volumetric measurements of the hippocampus, amygdala, thalamus and corpus callosum controlled for by intracranial volume. We found no direct effect of PTEs on structural changes in the hippocampus, amygdala or thalamus. In the corpus callosum on the other hand, we found a significant decrease in brain volume in the participants that had experienced PTEs. There was no evidence for indirect effects mediated by depression or anxiety on any of the brain structures. Our findings suggests that the participants from the Tromsø study that have experienced PTEs have structural brain changes in the corpus callosum and not in the investigated areas of the subcortex. It would be interesting to investigate this further to see what impact this can have on the development of other mental illnesses.