As Operation Enduring Freedom, the war on terror in Afghanistan, winds down and some 33,000 U.S. servicemen and servicewomen return from overseas in the next year, a plan announced by President Obama on June 22, the psychological issues that veterans face back home are likely to increase.

Some of the key psychological issues affecting the approximately two million American troops deployed to Iraq and Afghanistan since 2001 have been traumatic brain injury (TBI), depression and post-traumatic stress disorder (PTSD)—and the diagnoses often overlap. A 2008 report by the RAND Corp. think tank estimated that more than 26 percent of troops may return from the wars on terror with mental health issues.

It is reasonable to expect a continuation of these brain and mental health trends, only multiplied by the anticipated dramatic uptick in returning troops. On top of that, such issues also tend to crop up several months or even years after service members settle in, rather than directly after homecoming, as researchers learned following America's wars in the late 20th century. A false honeymoon can deceive health care workers and family into a perception that all is well among members of the military reentering society stateside.

After the withdrawal of U.S. soldiers from Vietnam in 1973 "the only thing that happened is that rates of problems went up," says George Mason University assistant professor of clinical psychology Keith Renshaw. "The longer people are back, the more people come forward as potentially struggling." A study in the April issue of the Journal of Affective Disorders showed that among service members injured in Iraq or Afghanistan, health care usage—and psychiatric problems—increased over time.

The influx of veterans from Iraq and Afghanistan into the military mental health system has yet to peak, but it is already well underway. There is some concern, however, that the health care system is unprepared to handle the care of returning troops. A 2010 report from the Institute of Medicine identified a "critical shortage of health care professionals—especially those specializing in mental health—to meet the demands of those returning from theater in Iraq and Afghanistan and their family members."

TBI is especially common: roughly 30,000 service members were diagnosed annually in 2008, 2009 and 2010, according to U.S. Department of Defense (DoD) figures. Most of those diagnoses were for concussions or other relatively mild forms of brain injury. PTSD is also worryingly prevalent—in a RAND survey, 13.8 percent of veterans and returning soldiers from Iraq and Afghanistan met the criteria for PTSD, meaning that some 275,000 U.S. service members may be affected in total.

The RAND report predicted that the mental health needs of returning Iraq and Afghanistan veterans will increase over time. "There are a lot of concerns that what we see now are underestimates, if anything," Renshaw says.

Many of the afflicted veterans will not seek help, and others will not do so for some time. "There's a lag time between when people serve and when they actually come in," says Shira Maguen, an assistant professor at the University of California, San Francisco, School of Medicine and a psychologist at the San Francisco Veterans Affairs (VA) Medical Center. "For many of those people there are a lot of barriers at this point, the biggest of which is probably stigma." Renshaw notes that some soldiers who remain active in the armed forces resist seeking help because they do not want to endanger their military careers by acknowledging psychological issues. Others seek help in civilian practice rather than in the military health system.

The DoD and the VA have taken steps to prepare for the forecast rise in PTSD cases, highlighting two approaches to treatment—cognitive processing therapy and prolonged exposure therapy—that studies have shown to be effective. And June 27 has been designated National PTSD Awareness Day. "They're rolling out a massive dissemination effort," Renshaw says. "But I don't think we're at the point that we're ready yet."

New veterans suffering from PTSD may well fare better than their predecessors who served in Vietnam, as the disorder was only recognized by the American Psychiatric Association in 1980. "I think we've learned a tremendous amount from Vietnam and from prior conflicts," Maguen says. "I think we're in a unique position now to deal with it."

Even with lessons learned from Vietnam and the Persian Gulf wars, however, veterans of Operation Enduring Freedom and Operation Iraqi Freedom present a special treatment challenge. In some ways the new crop of veterans have had similar combat experiences to Vietnam veterans. Both groups fought in wars without clearly delineated front lines, where ambush and insurgency are a constant threat. But the types of combat exposure have changed, as have the potential triggers for negative psychological reactions later in life. For instance, Renshaw says, the urban component of the wars on terror and the threat of improvised explosive devices have made driving and traffic jams problematic triggers for some veterans. "Our methodology is still evolving to catch up with the nature of these conflicts," he says. "I think this is something we're going to be working on and dealing with for a long time."