While psychiatrists debate and flex their theories and the nation wonders how Iranian captivity will affect the psyches of the 52 American hostages, there is one group whose readjustment they can look to for clues on the long-term effect of captivity: American prisoners of war in Vietnam.

No captivity experience is the same -- most Vietnam POWs endured a longer period of captivity, in more isolation and marked by more instances of torture than did the hostages in Iran -- but their track record of reentering society may offer clues as to how well the hostages will fare, say psychologists and psychiatrists familiar with POWs. Some POWs agree.

Some experts think that captivity itself, the stresses involved and the individual's capacity to handle those stresses -- not how long one is a captive -- are the most important factors in long-term emotional well-being.

"It's hard to tell how well they [the POWs] will do throughout their lives," Milt Richlan, a San Diego psychiatrist who tracked Navy fliers shot down in Vietnam in one five-year study. "There's no reason to believe they are walking time bombs. These are super people to begin with -- pilots and navigators who are very bright, very healthy, good athletes, survivors. But there are questions we can't answer: What happens when you put highly superior individuals under severe stress? What is the long-range effect on their health and on their careers?"

Seven years after the last of the POWs were repatriated, here are some of the findings:

Some 238 married Army, Navy and Marine POWs from Vietnam studied by the Navy Center for POW Studies in San Diego had a divorce rate two or three times higher than a similar control group of military couples. About one-third of those POWs got divorced their first year back from Vietnam -- psychologists, though, say their divorce rate never went above the civilian norm.

But, while they reported more conflicts, the couples who toughed it out also reported they had a stronger, better marriage five years later, said Edna J. Hunter, a San Diego college professor who served as acting director for the Center for POW Studies.

"The families who did well before imprisonment tended to do well afterwards," said Col. James F. T. Corcoran, chief of psychiatry at Brooks Air Force Base School of Aerospace Medicine, who studied some repatriated Air Force pilots. "Whatever the difficulties were, they tended to work them out. The marriages that were in trouble before, tended to be in trouble later."

Of the 325 repatriated Air Force fliers tracked for five years in a separate study, about one-fourth showed some psychiatric problems upon their return in 1973. Most of those showed some kind of transient stress, or adjustment reaction, as the hostages already have reported. But, as Corcoran says, "If you were away for seven years and came back, you might find it a little stressful, too. You don't have to be a psychiatrist to know that."

The biggest surprise for the wives questioned one year after repatriation in the Navy's San Deigo study was that their husbands actually had changed little -- that they had simply become "more of the same," said Hunter. Wives reported that their husband's basic personality didn't change, "but it became more firmly ingrained. If he was a rigid person [before captivity], he was more rigid; if he was tolerant, he was more tolerant, even after all the torture and isolation. They said it was as if he'd been in a time capsule."

The biggest surprise for the husbands was how much their wives had changed. In their absence, many wives had changed from obedient military spouses into hard-chargers, taking over family finances, disciplining the children, lobbying political leaders around the world for the husbands' release.

"It took many husbands two to three years to renegotiate their roles and recreate a well-functioning family group," said Hunter. "Rationally, they knew wives and chidren must have changed, but they fantasized that everything would be just like it was before." c

Of some 650-odd Vietnam POWs, there apparently were only two suicides, one a young Marine who shot himself the day he was officially charged with misconduct during captivity. Soon afterward, the White House pressured the Pentagon to dismiss all pending misconduct-during-captivity charges against American POWs. Only Marine Pfc. Robert Garwood, on trial in Camp Lejuene, N.C., faces such charges now.

While some POWs five years after release had emotional troubles ranging from personality disorders to marital problems to inability to keep a job, a significant number reflecting on their captivity three years later felt they had actually benefited from the experience.

"Most adjusted very, very well, far better than we anticipated," said Corcoran. "But it's hard to appraise. The people we see are those who are working and functioning and getting along very well."

Ursano agreed: "One cannot say the experience of stress necessarily leads to illness." Five years after release, he said, "the vast majority show no psychiatric distress -- and I'd expect the same of the hostages."

Nonetheless, other studies show that the physical and emotional problems arising from the stresses of captivity often don't emerge for more than a decade after release.

The traumatic stresses of torture, starvation diets and long isolation have not only shortened the life spans but emotionally crippled prisoners of war from World War II and Korea, as well as concentration camp survivors, according to a May 1980 Veterans Administration report that synthesizes a number of POW studies.

Length of time in captivity has not been found to be a factor in the most common emotional affliction -- a lingering post-traumatic stress syndrome, characterized by nervousness, flashbacks, irritability, depression and guilt. What matters was simply the fact of having been a captive.

The syndrome "occurs in a significant number of POWs interned just a few days, just as certainly as it does those interned a few years," the VA study reported. Such anxiety reaction accounted for 11 percent of all service connected problems in World War II veterans.

In concentration camp survivors, a related stress disorder called "K-Z syndrome" often doesn't emerge until 15 years after release.

Stan Sommers, 61, a disabled World War II veteran and president of American Ex-Prisoners of War Inc., an 11,000-member society, was a Navy carpenter's mate turned rifleman who fought off the Japanese on the beaches of Corregidor with a bolt-action Springfield until the island and the 8,500 Americans on it surrendered.

In captivity, Sommers, an athletic, 175-pound six-footer, dropped to 90 pounds and suffered from beriberi, a vitamin deficiency, and all manner of tropical diseases. He still suffers from fits of irritability, the desire to be left alone, a short temper and fatigue, and he has organ damage from malnutrition.

"Once you're captured -- whether you're a POW or a hostage -- you're equally helpless and until your release you're dependent on your captors for food, medicine, recreation, communication, every daily thing of life," Sommers says. "You lose your freedom, you lose your self-esteem."

Sommers believes the stress of being a captive also stunted the careers of most former POWs from World War II. "We're modern-day tragedies," he said.

He watched the American hostages come home on his TV in Marshallfield, Wis., and felt "nothing but compassion. Psychologically, they have suffered equally as we did. Their outward appearance looked pretty good, but their joy at returning home masks their real condition, both medical and physical. It's masked from their loved ones, the public and themselves. They believe they're OK and in some cases they might go unscratched, but I'll never figure out why."

But retired Air Force Lt. Gen. Jack Flynn, 58, says, "It's unfair to compare what we went through to the hostages," However, Flynn, a highly decorated ex-POW and the most senior American officer imprisoned in Vietnam (he spent six years in captivity after his F105 shot down on a bombing run over Hanoi) added, "I agree that anyone who is held hostage, even for 24 to 48 hours, will come out with a completely different impression of life. Whether you're a POW, or a hostage, or a victim of a terrorist, a robber or a rapist, you live in grave fear of your life, and it's going to mark you."

Many Vietnam POWs say it helped to jump right back into their jobs and families, to pick up where they left off. And, while their homecoming did not compare to the abundance of festivities enjoyed by the hostages, it was hearty in comparison to that of Vietnam veterans who were not POWs.

"Clearly the warm and joyous welcome that the hostages -- and the POWs -- got is necessary to their mental health, but the process of reaccommodation will be delayed by the euphoria," says Ursano. "We'll have to wait until [the hoopla] passes and the wife says, 'Hey, will you take out the garbage?' Then we'll see how well they readapt."