We don't know if post traumatic stress disorder has anything to do with this weekend's mass shooting of innocent people in Afghanistan.
But we do know the accused shooter had suffered a brain injury from a previous tour of duty.
Experts at Fresno VA's hospital are responding to a growing need for PTSD and traumatic brain injury treatments.
Many veterans who served in Iraq and Afghanistan are finding it hard to escape the demons of war.
"We went through mortar attacks on our camp. The I.E.D.'s and everything. It just became second nature to everything we were doing," said Army Sgt. Jarid Hilchey, who served two tours.
He was in Iraq when his Humvee was hit by an I.E.D. He was diagnosed with traumatic brain injury.
Even after that he went on to do a 15 month tour in Afghanistan.
"You start having dreams, hard time falling asleep, just constant memories about it. But you just think it's something natural, you don't think it's related to PTSD, you're just remembering it," said Sgt. Hilchey.
He says he didn't know anything was wrong, until he saw a doctor.
"I went and actually talked to a doctor because I was having a hard time sleeping, so he did inform me that it was in fact, PTSD," said Sgt. Hilchey.
"What happens is we're all born with a natural alarm system in our head. But when we're traumatized that alarm system gets stuck on. So what happens is the vets are in a chronically alert state, they have adrenaline flowing through them, they're ready to act, ready to move. And all of that is very important for survival in a combat zone," said Elizabeth McKee, a psychologist at Fresno's VA Hospital.
She says an increasing number of veterans are signing up for the PTSD program at the Fresno VA Hospital, which includes sessions with psychologists.
"50% of the vets coming into our program are Iraq or Afghanistan vets," said McKee.
But she says, most vets suffering from PTSD or traumatic brain injury don't go on killing sprees.
She worries attention on the recent tragedy may lead to some cases going untreated.
"It can add to the shame and stigma, and inhibit them from coming in because they don't want to be seen as crazy," said McKee.
The Fresno VA hospital treats more veterans with PTSD and traumatic brain injuries than any other VA hospital in California.
The hospital is expanding to meet the need - two new mental health buildings are under construction here at this hospital and more than a dozen mental health specialists are scheduled to come on board.
Around 20% of returning forces from Iraq and Afghanistan are likely to suffer from PTSD. That's about 60,000 people.