A treatment for PTSD, called EMDR, involves trying to enhance the right/left communication in the brain. This is done by eye tracking back and forth from left to right. I personally know two people that this was effective on, but there is a lack of hard data on whether this works or not in general.

However, the PTSD specialist that worked with these two individuals suggested that running (and walking) long distances can create the same effect since the person is continually scanning the environment. This would alleviate PTSD symptoms plus anxiety and depression in her patients.