Volumetric Differences of Thalamic Nuclei Are Associated With Posttrauma Psychopathology

Background: Previous investigations of whole thalamus and thalamic nuclei volumes in posttrauma psychopathology have been sparse and limited in scope and have yielded inconsistent results. To address this, volumetric estimates of whole thalamus and thalamic nuclei were obtained from structural brain magnetic resonance imaging scans from 2058 participants across 20 worldwide sites in the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Posttraumatic Stress Disorder (PTSD) working group. Methods: Thalamic volumes were compared in trauma-exposed participants with PTSD (n = 238), major depressive disorder (MDD) (n = 184), and comorbid PTSD+MDD (n = 618) and in trauma-exposed control participants (n = 1018). PTSD and MDD symptom severity, PTSD symptom clusters, and childhood trauma were similarly examined for associations with thalamic volume. Results: Participants with PTSD had smaller sensorimotor thalamic nuclei, while participants with MDD or comorbid PTSD+MDD had smaller mediodorsal (MD) thalamus volumes relative to control participants. Severity of PTSD and MDD symptoms negatively correlated with MD volume. A significant interaction between PTSD and MDD severity was found, such that MDD severity was positively associated with whole thalamus volume only among individuals with high PTSD severity. We observed both positive and negative volumetric associations for specific PTSD symptom clusters and childhood trauma subtypes. Conclusions: Whole thalamus volume and volumes of the sensorimotor and limbic thalamus may play an important role in the development of PTSD and MDD in the aftermath of trauma exposure. The interaction between PTSD and MDD symptoms and contrasting effects across PTSD symptom clusters and types of childhood adversity suggest that multiple neurobiological mechanisms are involved in shaping thalamic volume posttrauma.