Background: Posttraumatic stress disorder (PTSD) is a psychiatric disorder with considerable symptom heterogeneity and comorbidity that may develop after trauma exposure. The amygdala’s role in fear conditioning makes it an ideal candidate for investigations related to PTSD, and different volumes have previously been associated. However, the amygdala is a heterogeneous structure consisting of functionally distinct nuclei. Little research has focused on the specific associations between PTSD and these nuclei. We aimed to investigate the associations between amygdala nuclei volumes and PTSD and related measures.
Methods: We included amygdala subregion volume estimates for nine nuclei from ENIGMA-PGC PTSD (mean age= 35.76 years, 63% male) for individuals diagnosed with PTSD (n = 706) and control subjects without PTSD (n = 882). Nuclei volumes were compared across PTSD diagnosis, age of onset, severity, symptom cluster scores (re-experiencing, arousal and avoidance), comorbid major depressive disorder (MDD), and childhood trauma subscales.   Analyses were performed using ordinary least-squares regression, corrected for age, sex, intracranial, and whole amygdala volume.
Results: PTSD severity scores were negatively associated with the left lateral nucleus volume. Larger left and right central nucleus volumes were significantly associated with childhood physical abuse and neglect, respectively. The lateral, paralaminar and corticoamygdaloid transition area volumes were negatively correlated with specific PTSD symptom clusters.
Conclusions: Differences in select amygdala nuclei volumes among adults are associated with PTSD severity, symptom cluster scores, and physical trauma during childhood. Volume differences in the lateral and central nucleus associated with PTSD severity scores and childhood physical trauma demonstrate a nuclei-specific pattern consistent with their functional roles in  fear learning and expression.
Personnel: Mary S. Mufford, Dennis van der Meer, C. Lexi Baird, Delin Sun, Kevin LaBar, Raj Ramesar, Rajendra A. Morey, Ole A. Andreassen, Dan J. Stein, Shareefa Dalvie