Decreased uncinate fasciculus tract integrity in male and female patients with PTSD : a diffusion tensor imaging study.

Background: Posttraumatic stress disorder (PTSD) is a disabling psychiatric disorder that has been associated with lower white matter

integrity of tracts connecting the prefrontal cortex with limbic regions. However, previous diffusion tensor imaging (DTI) findings have

been inconsistent, showing high variability in the exact location and direction of effects. Methods: We performed probabilistic tractography

of the bilateral uncinate fasciculus, cingulum and superior longitudinal fasciculus (both temporal and parietal projections) in male

and female police officers with and without PTSD. Results: We included 38 (21 men) police officers with and 39 (20 men) without PTSD

in our analyses. Compared with trauma-exposed controls, patients with PTSD showed significantly higher mean diffusivity of the right

uncinate

fasciculus, the major white matter tract connecting the amygdala to the prefrontal cortex (p = 0.012). No other significant

between-

group or group × sex differences were observed. Mean diffusivity of the right uncinate fasciculus was positively associated with

anxiety symptoms (r = 0.410, p = 0.013) in patients with PTSD as well as with amygdala activity (r = 0.247, p = 0.038) and ventromedial

prefrontal cortex (vmPFC) activity (r = 0.283, p = 0.016) in all participants in response to happy and neutral faces. Limitations: Our specific

sample of trauma-exposed police officers limits the generalizability of our findings to other PTSD patient groups (e.g., civilian

trauma). Conclusion: Patients with PTSD showed diminished structural connectivity between the amygdala and vmPFC, which was correlated

with higher anxiety symptoms and increased functional activity of these brain regions. Our findings provide additional evidence

for the prevailing neurocircuitry model of PTSD, postulating that ineffective communication between the amygdala and vmPFC underlies

decreased top–down control over fear responses.