PTSD is a definite problem for some who have left high demand groups such as the JWs. Believe me you are not alone in this.
The manner in which most JWs live in a state of fear and most especially those who are DFed or even DA themselves would be enough to cause the symptoms of PTSD. Losing your entire support system/community and for many family as well as all friends would be considered outside the realm of normal human experience.
You might want to take a look at an article on my web page called <a href=" http://members.shaw.ca/leemarsh/soc-death.html">Social Death: The Practice of Disfellowshipping among JWs</A> that addresses the issue of leaving the JWs to an experience of social death. Although the article does not address PTSD and its direct relation to social death I think the link can be made between the two.
Hmmm I might need to do a bit more writing.
You might also find the article <a href=" http://members.shaw.ca/leemarsh/c-ptsd.html">Complex PTSD</A> interesting as it adds the perspective of a history of subjection to totalitarian control over a prolonged period.