LOS ANGELES -- Vietnam veteran John Otte did his best to forget the war.
He got married, raised two sons and made a career working at credit unions.
But as Otte neared retirement, memories of combat flooded back. Starting in 2005, he filed a series of claims with Veterans Affairs for disability compensation, contending that many of his health problems stemmed from the war.
The VA agreed, and now the 65-year-old with two Purple Hearts receives $1,900 a month for post-traumatic stress disorder and diabetes -- and for having shrapnel scars on his arms. His payments will rise to about $3,000 if the VA approves a petition to declare him completely disabled and unemployable.
"I've been sitting here waiting," he said.
Otte is among hundreds of thousands of veterans from the Vietnam era filing for damages four decades after the war. They account for the largest share of the 865,000 veterans stuck in a growing and widely denounced backlog of compensation claims -- some 37 percent. The post 9-11 wars in Afghanistan and Iraq account for 20 percent. The remainder are from the 1991 Gulf War, Korea, World War II and times of peace.
Basic demographics explain some of the filing frenzy. Vietnam veterans are becoming senior citizens and more prone to health problems. Any condition they can link to their military service could qualify for monthly payments -- and for many illnesses, it is easier for Vietnam veterans than other former troops to establish those links. Heart disease, Type 2 diabetes and several other afflictions common in older Americans are presumed to be service-related for Vietnam veterans because the government has determined that anyone who served on the ground there was likely to have been exposed to the herbicide Agent Orange, which is known to increase the risk of those conditions.
At the same time, changing attitudes toward mental health care mean that veterans suffering from PTSD and other psychiatric conditions are now more willing to come forward. The uncertainties of older age -- and possibly the decade-long spectacle of the current wars -- may in fact be triggering relapses of PTSD among some veterans.
Linda Bilmes, a public policy professor at Harvard University, said the filings are a cautionary lesson. "Wars have a long tail," she said. "The peak year for disability claims from Vietnam has not been reached yet."
By comparison, payments to veterans of World War I, which ended in 1918, were highest in 1969. Bilmes said the peak for the wars in Afghanistan and Iraq is likely to occur around 2050.
VA statistics show that annual compensation to veterans from the Vietnam era more than doubled between 2003 and 2012, reaching $19.7 billion of the total paid to veterans that year of $44.4 billion.
Of the roughly 320,000 Vietnam veterans in the backlog, about 40 percent are making claims for the first time. The rest already receive some compensation. Veterans who are denied can reapply indefinitely to increase their payments as existing conditions get worse or new ones emerge.
In recent years, veterans have had an easier time winning disability pay for several illnesses.
In 1991, Congress enacted a law guaranteeing compensation to any veteran who served on the ground in Vietnam and went on to develop certain types of cancer or a skin condition known as chloracne -- diseases linked to Agent Orange exposure.
As more scientific evidence has emerged, the VA has added 11 new conditions to the Agent Orange list, including Type 2 diabetes, prostate cancer and ischemic heart disease. Diabetes has become one of the most common conditions among Vietnam veterans receiving compensation. Over the last nine years, the number of cases rose from 135,000 to nearly 323,000 -- more than 10 percent of the service members who went to Vietnam.
Many qualify for multiple ailments. The number being compensated for hearing loss -- often tied to not having used ear protection -- rose by more than 236,000 since 2003.
Over the same period, nearly 184,000 joined the ranks of those being paid for PTSD. Nearly a third were added after 2010, when the VA loosened its requirements so that veterans no longer had to document specific events such as killings or ambushes that traumatized them. Having lived under threat qualifies anybody with a current diagnosis.
PTSD did not become a formal psychiatric diagnosis until 1980, when the Vietnam War was long over. It was highly stigmatized at the time, but the wars in Afghanistan and Iraq have made it more acceptable for veterans of all eras to seek treatment and compensation.
Vietnam War medic Shad Meshad, head of the National Veterans Foundation, said he urges veterans to file claims, telling them: "You've suffered for 40 years."
Even for veterans who led productive lives after the war, the psychological trauma can lurk in the background, said John Wilson, a psychologist at Cleveland State University and expert on PTSD and Vietnam veterans.
"Many don't sleep well," Wilson said. "If they hear a noise at night, they sit in the stairwell with a 9 millimeter to see if somebody is there."
The recent wars also may be causing relapses. Wilson's research shows that watching news reports about the U.S. involvement stirred up painful memories for some Vietnam veterans.
In 1986, researchers estimated that about 500,000 of the 3.1 million men who served in Vietnam were suffering from PTSD. Dr. Charles Marmar, a psychiatrist at New York University helping lead new research into the disorder, said that although some people with PTSD get worse over time, most improve. Life changes such as retirement or death of a spouse, however, can unleash old ghosts. "The deeper they get into retirement, the more they think about the past, and the less they think about the future," Marmar said.
Rich Dumancas, deputy director for veterans benefits at the American Legion, said the bad economy also drove claims as veterans lost jobs. "They needed to make ends meet, so they started talking to me about their disabilities," said Dumancas, who spent most of the last decade as a government advocate for veterans in Duluth, Minn.
Being approved for disability compensation also increases access to the VA health care system, which generally has lower out-of-pocket costs than Medicare.
VA officials say the agency rejects many new claims and that they do not believe the surge in claims signals abuse of the system. "There have been isolated cases where fraud has been identified," said Edna MacDonald, head of the VA benefits office in Nashville, Tenn. "But we have a lot of safeguards in the system."
Otte, the 65-year-old hoping for a full disability rating, said the war left him a changed man -- angrier, unable to forge close friendships, wracked with guilt for surviving while many other men in his Army unit were killed. But he managed to live productively, settling in L.A.'s Harbor City community.
His wife, Benedicta, said he never told her much about the war, but it is clearly a source of distress. When the family went to see the 1986 Vietnam movie "Platoon," he had to leave the theater.
Sometimes he wakes her up with cries of "no, no, no" in his sleep, she said. His nightmares started more than a decade ago and grew more frequent over time, he said. In the most common dream, he is under enemy fire but can't shoot back. His M-16 rifle is jammed.
A friend advised him to apply for disability compensation and seek care at the VA in Long Beach, where he now attends a group therapy session once a week and undergoes treatment for pain, eye problems and other complications of diabetes.
His latest disability filing has been pending since 2010.
"I should be at the front of the line," he said. "I was a guy walking around in the jungle for a year."