Reduction of anterior cingulate in adults with urban violence-related PTSD

Background: To evaluate differences in limbic structure volume of subjects exposed to urban violence during adulthood, between those who developed posttraumatic stress disorder (with PTSD) and resilient matched controls (without PTSD).

Methods: Limbic volumetric measures of 32 subjects with PTSD and 32 subjects without PTSD who underwent brain MRI were analyzed in an epidemiological study in the city of Sao Paulo. The hippocampus, amygdala, cingulate, and parahipocampal gyri volumes were estimated using FreeSurfer software. We also investigated the association between limbic volumetric measurements, symptom´s severity, and early life stress history (measure by Early Trauma Inventory - ETI).

Results: Subjects with PTSD presented reduced volume of the right rostral part of the anterior cingulate, compared to subjects without PTSD, after controlling for intracranial volume, ETI, and depressive symptoms. Subjects with PTSD presented larger bilateral hippocampus and right amygdala, but secondary to the higher ETI. In PTSD group there was a positive correlation between ETI with bilateral hippocampus, bilateral amygdala, and left parahippocampus.

Limitations: First, the cross-sectional study design precludes causal interpretation of limbic structure reduction in PTSD, consequence of PTSD, or other life events. Finally, since the sample size was not sufficiently large, we could not observe whether or not limbic structure volume could be related to the type of trauma.

Conclusions: The present study provides evidence of a reduced anterior cingulate volume in subjects with PTSD than in resilient subjects exposed to urban violence. Enlargement of hippocampus and amygdala volume was observed in subjects with PTSD, however secondary to early trauma experience.