Cerebellar Volumes Are Smaller in Veterans with PTSD and a History of Mild Traumatic Brain Injury, but Not Mild Traumatic Brain Injury Alone

= 0.165). Follow-up exploratory analyses of subregional cerebellum volume differences suggested that volume differences in comorbid mTBI-PTSD were primarily localized to the posterior lobe (crus I, lobules VIIB, VIIIB). In sum, in a sample of combat veterans, mTBI was associated with a smaller volume of the cerebellum, but only when comorbid with PTSD. Consistent with recent work, exploratory subregional analyses indicated that volume differences were primarily attributable to regions of the cerebellum most prominently involved in cognition and emotion. These results underscore the profound effects of PTSD on brain health in military veterans and suggest that mTBI may not produce long-lasting structural damage to the cerebellum. Future work is needed, as it remains possible that subtle cerebellar volume changes may emerge in specific subgroups or as a function of injury-related factors (e.g., mechanism of injury, time since injury) not fully captured in the present study.