Philip Paolini served four years in the Vietnam War as a marine. In the years since then, he's faced a number of hardships, including post-traumatic stress disorder (PTSD), substance abuse and homelessness.
And Paolini's story is far from uncommon. New research shows that four decades after the Vietnam War ended, more than 270,000 veterans who served in the war zone suffer from symptoms of PTSD, a mental health condition characterized by painful flashbacks, severe anxiety, and uncontrollable thoughts about the disturbing events they experienced.
The study, published online Wednesday in JAMA Psychiatry, also found that at least one-third of those veterans exhibiting symptoms of PTSD suffer from major depression, as well.
Researchers from NYU Langone Medical Center followed up with Vietnam War veterans who had participated in a study from 1984 to 1988. Of the 1,839 men and women still alive from the original study, over 1,400 participated in at least one phase of the new study, which involved a health questionnaire, health interview and clinical interview.
The study authors used three different scales to measure PTSD. Depending on the method, the results suggest that between 4.5 percent and 11.2 percent of the male Vietnam veterans and 6.1 and 8.7 percent of the female vets are experiencing serious PTSD symptoms today.
About 16 percent of veterans in the study reported an increase of more than 20 points on a PTSD symptom scale, while only 7.6 percent reported a decrease of greater than 20 points.
"The primary message is that the majority of men and women who served in Vietnam are resilient across 40 years," lead study author Dr. Charles Marmar told CBS News. "However, equally important, the minority of individuals who were symptomatic 15 years ago or more are likely to have increases rather than decreases in the severity of the symptoms. A case of PTSD that is chronic -- lasting more than five years after war -- is likely to persist because most spontaneous recovery occurs in the first two to three years."
He pointed out that although rates of overall depression are very low among Vietnam veterans today, one third of those with PTSD also have major depressive disorder, compounding the mental illness.
In addition, the ordinary stresses of aging, including increasing health problems and declining cognitive function, tend to exacerbate PTSD symptoms even more, the authors said.
"Also impacting PTSD are other sociological factors of aging, such as retirement which can lead to greater social isolation and opportunities to reminisce on memories," Marmar said. "All of these make it more difficult to suppress and control traumatic memories."
Now 70-year-old veteran Joe Jackson says that when he got home from a year of combat in Vietnam, "I tried to bury it." But ignoring the trauma didn't work; instead he experienced anxiety and outbursts of rage. He and his family suffered for 20 years before he got help.
Experts say that the research highlights what may be ahead for other generations of veterans and the importance of getting treatment to those who need it.
"For Vietnam veterans, I would say they really did not have services for PTSD available to them when they came home, and if they haven't received treatment it's never too late," said Dr. Charles Hoge, senior scientist at the Walter Reed Army Institute of Research. "For Iraq and Afghanistan veterans, there are many more treatment options available."
At his daughter's urging, Jackson finally got counseling, and he says it has helped. "It made it a lot easier for me to accept," he said.
As for Paolini, about two years ago he went Veterans Inc., a non-profit organization aimed at ending homelessness among veterans, to get support. He received counseling and medication and said he has since turned his life around. Despite his struggles, he said he is proud to have served his country.
"I don't choose to live in the past," he said. "I don't choose to live in the future. I choose to live in the moment now and make the best day I can every day."