The neurobiology of brain recovery from traumatic stress: A longitudinal DTI study

Background Previous studies demonstrated decreased brain microstructure integrity in people that were exposed to extreme life stress but did not meet posttraumatic stress disorder (PTSD) diagnostic criteria. It is unclear how the brain recovers from traumatic stress in these trauma-exposed non-PTSD people (TENP). Methods Twenty-two TENP individuals were recruited from the most affected area of Wenchuan quake, and scanned twenty-five days after the quake and at a two-year follow-up. Tract-based spatial statistics was used to examine brain microstructure changes over the two years. Correlation analyses were conducted to investigate relationships between brain microstructure changes and both stress recovery and demographic factors. To assess DTI stability, fifteen healthy subjects were scanned twice in a year and analysed similarly. Results Significantly increased fractional anisotropy (FA) was found in the left posterior limb of internal capsule, left superior and posterior corona radiata (SCR and PCR), and left external capsule. The FA increase of these regions was primarily a result of radial diffusivity reduction. Recovery in symptoms was positively correlated with FA increase of SCR. Changes were related to participant age and sex. No DTI measures were changed for the healthy subjects. Limitations Generalizability of the findings was constrained by the relatively small sample size. Conclusions The TENP individuals showed a recovery from the trauma over the follow-up, and that was accompanied with increased brain microstructure integrity in fiber tracts primarily involving corticostriatal networks. These changes may contribute to the psychological resilience to a severe life stress that led to PTSD in quake victims. In particular，this study adds to Psychoradiology, which is a promising subspecialty for clinical radiology focusing on psychiatric disorders.