Many of his fellow veterans in his New Jersey hometown battled drug problems and nightmares. Some committed suicide. He says his own twin brother, who went to war the following year, came back a changed person - debilitated by anxiety and delusions.

"We were expected to soldier on," Boscarino says. "We did the best we could."

Today, those symptoms are well-known as post-traumatic stress disorder (PTSD). And Boscarino, 62, has made it his life's work to understand the problem.

Now an epidemiologist, he is among the organizers of a national conference to be held tomorrow on the still-mysterious illness, at Geisinger Health System in Danville, Pa.

The event's focus is on getting the best care for veterans from rural areas, where there are fewer mental-health services available and where family doctors may be less familiar with the symptoms of combat stress. Rural vets are well-represented among the National Guard troops and reservists serving in Iraq and Afghanistan.

But misunderstandings about the illness persist in rural and urban areas alike, say Boscarino and other experts who are slated to speak tomorrow.

Some still see the problem as the result of a weakness in character, or perhaps a lack of self-discipline, says keynote speaker Charles Figley, director of the Florida State University Traumatology Institute. It is neither.

"It's an injury," says Figley, himself a Vietnam vet. "Its effects can be permanent unless something is done pretty quickly."

Just what should be done is a matter of debate.

In a review of medical literature completed last year, an Institute of Medicine committee found no evidence that drugs have been effective against the disorder. Some forms of psychotherapy also remain unproven, the committee members found - though they emphasize that with more careful scrutiny, some of these current therapies may indeed turn out to be beneficial.

Boscarino, who grew up in working-class Paterson, N.J., and served with an Army artillery unit in Vietnam, is determined to find the biological underpinnings of the disease.

There is evidence that genetics play a role. Other research suggests that those with higher intelligence are less likely to succumb to PTSD. Still other scientists contend that some cases of the disorder are in fact a different condition defined by several of the same symptoms: mild traumatic brain injury.

Last year, Boscarino reported a curious finding: Vets are more likely to suffer from PTSD if they are ambidextrous. The results, from a study of 2,490 men who served in Vietnam, were published in the journal Psychosomatic Medicine.

But Boscarino's twin brother, John, is not ambidextrous, and he has the same genes. Why would one brother be severely affected by the war and the other not?

The epidemiologist declined to talk about his brother's case in detail, but said his twin was likely exposed to a higher level of stress, having seen heavy combat in the 1968 Tet offensive. After years of refusing treatment, he is now getting help at a VA facility, Boscarino said.

Whatever the cause, severe stress leads to hormonal changes and inflammation, which in turn can have lasting consequences.

One possible result is heart disease, which Boscarino and others have reported in the past.

But heart attacks themselves are stressful, so he wanted to determine if PTSD was leading to heart disease and not the other way around.

Recently, Boscarino did a follow-up study, excluding veterans who had preexisting cardiovascular issues. And once again, vets with PTSD were more likely to have heart disease. The results are to be published later this year.

Separately, Boscarino also has shown that PTSD is just as strong a "marker" for poor health as having an extremely high white-blood-cell count.

"PTSD predicts whether I'm going to be dead or alive in 10 to 15 years just as well as having bad blood-test results," Boscarino said. "They're both deadly."

Boscarino still wonders if there is something he could have done in the summer of 1967, when he drove his brother to Fort Dix to catch a plane to Saigon.

Perhaps he could have given more advice on how to cope with the horrors of combat, or how to listen for an incoming mortar round.

"I had a feeling he wouldn't make it back," the researcher said.

Physically, he did. Mentally, Boscarino said, his brother is still in Vietnam.

at 215-854-2430 or tavril@phillynews.com.