Welcome to the forums, and thank you for your service! There have not been very many studies that have specifically focused on pipe smokers exclusively, but as I recall, one from a while back showed that pipe smokers tend to live longer than non-smokers, something the study at least partially attributed to the relaxing, blood pressure reducing effects of the smoking process. I dunno about PTSD, but I can say for sure that smoking a pipe helps reduce my anxiety and helps with my depression. I have a buddy who served in Iraq and deals with pretty serious PTSD from his experiences, and his VA docs have given him a permanent subscription for Lorazepam, from which he has developed a pretty serious addiction. It seems like a lot of addictions in the Vet world start from prescriptions from a VA doc (opiates, benzos, etc.), so I sometimes wonder if the VA medical system as a whole could use a more holistic approach, relying a little less on pharmaceuticals.