Altered functional connectivity in the brain default-mode network of earthquake survivors persists after 2 years despite recovery from anxiety symptoms Running title: Long-term traumatic impact on survivors

While acute impact of traumatic experiences on brain function in disaster survivors is similar to that observed in post-traumatic stress disorders (PTSD), little is known about the long-term impact of this experience. We have used structural and functional magnetic resonance imaging to investigate resting-state functional connectivity and gray and white matter changes occurring in the brains of healthy Wenchuan earthquake survivors both 3 weeks and 2 years after the disaster. Results show that while functional connectivity changes three weeks after the disaster involved both frontal-limbic-striatal and default-mode networks, at the 2-year follow up only changes in the latter persisted, despite complete recovery from high initial levels of anxiety. No gray or white matter volume changes were found at either time point. Taken together, our findings provide important new evidence that while altered functional connectivity in the frontallimbic-striatal network may underlie the post-trauma anxiety experienced by survivors, parallel changes in the default-mode network persist despite the apparent absence of anxiety symptoms. This suggests that long-term changes occur in neural networks involved in core aspects of selfprocessing, cognitive and emotional functioning in disaster survivors which are independent of anxiety symptoms and which may also confer increased risk of subsequent development of PTSD.