Answer: The hippocampus may shrink due to over exposure to neurotransmitter and hormones.
Step-by-step explanation:
The posttraumatic stress disorder( PTSD) can be defined as the mental condition which is triggered by the terrifying events either by experiencing it or witnessing it.
Symptoms includes: nightmares, flashbacks and some uncontrollable thoughts about the events.
This is caused because of release of excessive hormone and neurotransmitter which tends to shrink the hippo campus of brain.