If one judged from stories in the media, one would think the main cause of Post-Traumatic Stress Disorder is wartime combat. In fact the most common cause of PTSD is sexual assault.
PTSD is common, and, I believe, underdiagnosed. That's because its symptoms include anxiety and what may look like depressive symptoms. Furthermore, for many years, and perhaps continuing into the present, PTSD was thought of as an illness relating to a specific trauma experienced in the recent or moderately recent past. Some psychiatrists don't look closely at the causes of symptoms and just prescribe a pill for what the symptoms look like. It may take time in therapy for a patient to reveal the complete history of the trauma(s).
Many combat veterans are apparently now receiving disability benefits for PTSD. The illness is treatable, and in my experience, most people recover. I've wondered what our society would look like if everyone who had PTSD received disability benefits and stopped working. Whole industries might grind to a halt, because childhood trauma and sexual violence throughout the life cycle, are common. Perhaps our society doesn't take PTSD suffered by victims of childhood trauma or rape in adulthood as seriously as we take PTSD suffered by combat veterans. Of course, many combat veterans have other disorders on top of PTSD, including Traumatic Brain Injury (TBI). TBI can cause behavioral and mood disturbance and may be misdiagnosed.
I've worked with many combat veterans as well as a large number of people who have experienced childhood trauma. In fact, the vast majority of my patients have experienced some sort of childhood trauma--it's the main reason people come to therapy. Not everyone who has experienced trauma develops PTSD, however. Many factors can affect whether or not someone develops PTSD. I've noticed that many cases of long-term PTSD involve unresolved guilt feelings.
It can be important to distinguish acute stress symptoms from PTSD. It's normal for anyone to experience certain symptoms after experiencing a life-threatening event or witnessing a fatal or life-threatening event. These symptoms can include anxiety, flashbacks and fear of the situation or locale in which the event took place. In most cases the symptoms go away after a few weeks. If not, the individual can be diagnosed with PTSD and will need treatment.