Association of abnormal white matter integrity in the acute phase of motor vehicle accidents with post-traumatic stress disorder

Abstract

Background: A small portion of the Motor vehicle accidents (MVA) survivors would develop post-traumatic stress disorder (PTSD), which would cause substantial social function loss. How to identify those high-risk MVA survivors in the acute phase of the trauma is the first step to prevent the onset of PTSD. In the present study, we studied white matter integrity of subjects post to MVA by diffusional tensor imaging (DTI).

Methods: To investigate whether the integrity of the white matter was impaired in the acute phase of the MVA among survivors who later develop PTSD and whether it could predict the severity of PTSD while being diagnosed. MVA Survivors were recruited to get trauma-specific clinical assessments and received DTI scan within 2 days from the MVA. These survivors were divided into 2 groups, PTSD group and trauma control (TC) group based on the clinical follow-up interview. Tract-Based Spatial Statistics (TBSS) was carried out to investigate difference in white matter integrity between 2 groups within DTI parameter maps. White matter integrity was measured by using fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radical diffusivity (RD).

Results: Compared with TC group, PTSD group showed lower FA value in multiple regions of both hemispheres, mainly involving anterior thalamic radiation, cortico-spinal tract, forceps minor, uncinate, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, cingulum and superior longitudinal fasciculus. Increased RD was also detected in PTSD group in the posterior part of right hemisphere, involving forceps major, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, cingulum, hippocampus and superior longitudinal fasciculus. The baseline FA and RD values correlated with Clinician-Administered PTSD Scale scores at clinical follow up.

Conclusion: MVA survivors who later developed PTSD had more abnormalities in white matter integrity in the acute phase than those non-PTSD MVA survivors. Imaging markers of white matter integrity might be helpful in early identification of MVA survivors at high risk of PTSD.

Limitations: Larger sample size in our extensive study is needed to confer a robust inference and image data at follow up are needed to observe the longitudinal changes of white matter integrity.

Keywords: Diffusion tensor Imaging; Motor vehicle accidents; Post-traumatic stress disorder.