The Army is keeping mum on whether the Army sergeant who went on a rampage in Afghanistan has ever been evaluated or asked for evaluation for PTSD, but it is well known that in recent years the culture of the military has been to sweep such problems under the rug, in order to redeploy as many soldiers as possible. The Army has acknowledge that the soldier had been diagnosed with a "traumatic brain injury" after a vehicle rollover in Iraq. The soldier was on his fourth combat tour.
Moreover, the base from which he deployed, Ft. Lewis-McChord, has been plagued with soldier suicides and stateside violence, and is under investigation for allegedly dismissing large numbers of legitimate claims of PTSD. 
David Wood of Huffington Post  said yesterday:
Lewis-McChord has been plagued by high rates of suicide and PTSD and is the home base of the notorious "kill team'' of soldiers accused of killing three Afghan civilians for sport two years ago. The GI newspaper Stars & Stripes once called Lewis-McChord "the most troubled base in the military."
In late 2010 The Hill  brought attention to the problem, interviewing Iraq veteran Ethan McCord, who came into the national spotlight that year as the soldier who saved two wounded children after a controversial Apache helicopter attack in Baghdad in 2007 , which was captured on film and released to Wikileaks. McCord was participating in a campaign by Iraq Veterans Against the War to stop the redeployment of wounded soldiers.
"“I was denied treatment for the mental and physical wounds I sustained in battle, like so many others,” says Ethan McCord... “This campaign is critical for soldiers because we are asserting our right to heal. Now, the government has a choice- will it recognize our right to heal, or continue to deny it?” McCord, who served in Iraq with the Bravo Company 2-16 made infamous by the Wikileaked “Collateral Murder” video, is actively involved in fighting for veterans' rights as well as reparations for Iraqi civilians who his unit harmed."
The Hill said:
An estimated 20-50% of all servicemembers deployed to Iraq or Afghanistan struggle with PTSD, totaling 350,000 to 900,000 troops. Soldiers report inadequate access to treatment, domestically as well as while deployed. Recently, Fort Hood in Texas saw four decorated combat veterans commit suicide in a single week. Mental health screening is often cursory and anonymous, providing no real assessment of a unit's fitness even between deployments.
In an article today in New Scientist , Debora MacKenzie says of the recent incident: "recent research suggests such disasters are just waiting to happen."
US army researchers have found that after Middle East deployment, 10 to 20 per cent of soldiers suffer severe post-traumatic stress disorder (PTSD), a type of chronic anxiety including flashbacks, emotional numbing and anger.
They warned in 2010 that these veterans report three times more aggressive outbursts than the pre-deployment average, and that PTSD may not emerge until 12 months after returning from deployment, when soldiers are often deployed again, leading to cumulative stress. We don't know if the rogue soldier had PTSD. However, he was on his fourth deployment from Lewis-McChord military base in Washington state, which has suffered high rates of PTSD, violence and suicide among soldiers with multiple deployments.
In the summer of 2010, veterans associated with the anti-war Under the Hood Cafe outside of Ft. Hood, TX, were protesting the redeployment  of PTSD-wounded soldiers in the 3rd Armored Cavalry Division, in which many of them had served, warning that such redeployments endangered both the unit and the mission. Michael Prysner of IVAW  wrote that year:
The rising trend of active-duty military suicides culminated in June with the highest monthly total ever in the U.S. military. There is no debate over the cause of the suicide epidemic: repeated deployments with severely inadequate treatment in between. The U.S. military has been exposed for intentionally denying GIs a post-traumatic stress disorder diagnosis to keep the number of deployable troops at a high level.
Ft. Hood veteran-activists attempted to block the busses carrying the 3rd Armored Cav as they departed for the air transport. From Stand Together: 
"many soldiers facing deployment are known to be unfit for combat due to injuries sustained in prior tours. The Peace Movement must not let this stand!
Without releasing the suspect's medical records or providing anything but the most rudimentary information about him, the Army seems to have gone in to spin mode, blaming "mental illness" through a headline interview with a former Army psychiatrist, who has never treated the suspect.
Reporting a diagnosis from afar, CNN  said today:
"Post-traumatic stress disorder has a cluster of symptoms, and violence, or violence against, others is not usually considered part of that diagnosis," said Paul Newhouse, a professor of psychiatry at Vanderbilt University and a former Army psychiatrist. "So I think it's more likely that we're going to discover that there was some either psychotic illness or delusional condition or some evidence that this person was more seriously deranged or impaired than we would typically see in PTSD."
This should come as no surprise. Lt. Col. Daniel Davis in his recent devastating report  on the situation in Afghanistan fires repeated volleys at the Pentagon's current regard for the truth, summing up his experiences by saying "We seem significantly challenged to tell the truth in almost any situation." In one startling passage after another, Davis reveals the mindset of top command:
"In all probability our leaders do not consider what they are saying to be "lying" per se, but an effective part of "Information Operations (IO)" designed to protect the support of the American people...""
Lt. Col.Davis explains:
"IO (Information Operations) becomes a core competency. The importance of dominating the information spectrum explains the objective of transforming IO into a core military competency on a par with air, ground, maritime and special operations."
Davis, a field-grade officer, describes placing this political component of war-fighting on par with what military organizations are trained to do as nothing short of "remarkable."
This tragic incident for all involved only highlights the urgency of withdrawing combat troops out of Afghanistan, to be replaced by reparations in the form of funding for the honest and competent Afghan National Solidarity Program , which will hire men so they won't have to work for the Taliban which pays $10 a day  in a place where unemployment is 50% and higher outside of Kabul. Given that it has been determined that the US Department of Defense is likely the biggest funder  of the insurgency, through payments made  to insurgent groups to allow military supply convoys to travel unhindered, the war is a farce which could be ended tomorrow without sacrifice to American national security interests.
Child malnutrition has edged up in the country from 54% in 2005  according to the World Bank to 60% today  according to Save the Children. This winter dozens of children froze to death  in the squalid refugee camps in and around Kabul, the most secure area in the country.
Reparations for 30 years of being a pawn of the US in what Zbigniew Brzezinski calls "the Great Game"  is the best bulwark against the return of the Taliban, which is still roundly despised in Afghanistan. What is taking place now is what is endangering national security.
Ft. Hood Protest Against Deployment of PTSD Soldiers, 2010:
The author is co-founder of Jobs for Afghans .