Hey Batgirl, I just don't believe that hippocampus size relates specifically to PTSD. To me, its not proven research. I know its a part of the brain associated with memory, but fail to see how its size matters, especially if there is no "before" MRI to compare its current size to (to demonstrate shrinkage). To me, you need to have many MRI's that show 'before trauma and after trauma' to compare... I don't think that's available. And because of this, I don't know how 'shrinkage' can be determined in the first place and also tagged to PTSD. Is everybody's heart the same size as their fist??