Mean diffusivity in the amygdala correlates with anxiety in pediatric TBI.

Traumatic brain injury (TBI) and orthopedic injury (OI) patients are prone to anxiety and mood disorders. In the present study, we integrated anatomical and diffusion tensor neuroimaging to investigate structural properties of the amygdala and hippocampus, gray matter regions implicated in anxiety and mood disorders. Children and adolescents were evaluated during the late sub-acute phase of recovery following trauma resulting from either moderate to severe TBI or OI. Mean diffusivity (MD) of the amygdala and hippocampus was elevated following TBI. An interaction of hemisphere, structure, and group revealed that MD of the right amygdala was elevated in females with TBI. Self-reported anxiety scores were not related to either volume or microstructure of the hippocampus, or to volume or fractional anisotropy of the amygdala. Left amygdala MD in the TBI group accounted for 17.5% of variance in anxiety scores. Anxiety symptoms may be mediated by different mechanisms in patients with TBI or OI.