I volunteered as VA facilitator for a PTSD group for eight years because of my combat experience in Vietnam and could relate to the vets' issues.
For the outsider looking in there are five symptoms that can help reveal whether a veteran has PTSD or not:
1. Relationship Issues: multiple divorces or breakups with loved ones due to the unwillingness by the veteran to admit he has a mental issue.
2. Drug or Alcohol Abuse: veterans literally try to drown their war demons with booze or by taking drugs.
3.Psychosomatic: individuals may have health issues such as high blood pressure due to mental stress.
4. Depression: with an overland of mental issues the individual becomes despondent. This can lead to suicide.
5. Despair: with no end in sight to the anguish the individual loses hope and contemplates suicide.
In my novel Legacy of War the main character deals with mental anguish from war.