For weeks, investigators have pored over clues in the hopes of understanding why 64-year-old Stephen Paddock decided to open fire on thousands of concert goers in Las Vegas last month, killing 58 people.
But more than a month after the shooting, officials have given no indication that they know anything about Paddock’s motive.
This month, as part of the autopsy, Stanford University researchers are investigating if there is any sign of brain damage or disease in Paddock’s brain.
Damage or injury to certain areas of the brain can be associated with increased impulsiveness, lack of judgment, and other symptoms that can affect a person’s actions.
“Multiple forensic analyses will be performed on Paddock, including a neuropathological examination of brain tissue at the Stanford University Department of Pathology, which is one of the County Coroner’s contracted neuropathology laboratories,” Clark County Coroner John Fudenberg said in a statement sent to Healthline.
How brain damage affects behavior
There are certain brain diseases or injuries that are associated with an increase in aggressive or even criminal tendencies, according to experts.
However, finding a simple answer to why a person would meticulously plan a mass shooting that killed dozens is likely impossible from a physical exam of brain tissue alone.
Dr. Hannes Vogel, director of neuropathology at Stanford University Medical Center, who will examine the tissue told The New York Times that it’s unlikely the exam will result in a clear answer to why Paddock did what he did.
“I think everybody is pretty doubtful that we’re going to come up with something,” Vogel said. “The possibilities, neuropathologically, for explaining this kind of behavior are very few.”
Dr. Ryan Darby, an assistant professor of neurology at Vanderbilt University Medical Center, said investigators most likely will look for signs of a neurodegenerative disease or lesions on the brain.
They will also likely search for one form of disease caused by misfolded proteins called frontotemporal dementia.
“It’s associated with crimes,” Darby explained.
He said more than one-third of these patients are estimated to have committed a crime.
“But most of them are nonviolent,” he noted.
He said that this disease, which is more common in people between the ages of 45 to 65, can lead people to commit “almost silly or reckless crime,” including things like stealing something small such as a candy bar, trespassing, or indecent exposure.
“Violence has been reported in those patients, but it’s usually rare,” he said.
Darby explained that the areas of the brain affected by this disease influence “our behavior, our emotion, our decision-making, our personality.”
Although Paddock has been reported to have died by suicide due to a gunshot wound to the head, Darby said researchers could still look for clues in the brain tissue.
He explained frontotemporal dementia is a diffuse enough disease that it likely would still be found in tissue.
Additionally, he said any tumor in the brain that affected Paddock’s action would likely be large enough that it could be found in tissue.
However, “it does depend a little bit on where in the brain the bullet wound went through,” Darby said. “If it went through and really damaged most of the frontal and temporal lobes, then it might be very difficult” to tell.
Other kinds of neurodegenerative disease include chronic traumatic encephalopathy, or CTE, which has been linked to a history of concussion or other trauma to the head. The condition, which has been found in numerous football players and other athletes posthumously, is associated with “impaired judgment, impulse control problems, and aggression.”
However, Darby said that unless Paddock had a history of head trauma, it’s unlikely he’d be diagnosed with CTE.
Researchers may also look for lesions to the brain caused from stroke or tumors that could impact specific areas that control personality aspects like impulsivity or aggression.
Can a brain tumor result in mass murder?
In one famous case, a mass murderer was found to have had a brain tumor, but it’s still unclear if that had anything to do with his actions.
In 1966, Charles Whitman killed 14 people from the clock tower at the University of Texas in Austin.
Whitman, who had exhibited headaches and feelings of hostility prior to the shooting, wrote in a note that he wanted his body autopsied.
He was found to have a small brain tumor in his autopsy, according to reports.
A commission convened by the Texas governor to investigate the shooting determined that the virulent form of brain cancer called glioblastoma multiforme may have contributed to Whitman’s ability to “control his actions and emotions” but that “the relationship between the brain tumor and his actions were unclear.”
Vogel also told The New York Times he’s unaware of brain tumors being linked to other mass killing.
“I don’t think I ever heard in my own experience of someone on a homicidal rampage because they had a brain tumor,” Vogel told The New York Times.
As investigators look for a clear reason for Paddock’s actions, Darby said from what he’s seen reported it’s unlikely researchers will find anything that could be an explanation for Paddock’s actions.
“I think that the most likely thing that will come out of this is that they won’t find anything that’s wrong,” Darby said.
He explained that Paddock’s methodical actions to prepare for the shooting in addition to his behavior with family and friends don’t suggest a condition like frontotemporal dementia, where a person loses judgement and impulse control.
“For these other types of conditions, it’s usually something where the symptoms are pretty apparent to family members and friends,” he said of a patient’s personality changes.
Darby said if investigators do find damage to the brain, even the areas that control judgement and emotion, it doesn’t automatically explain why someone would want to commit something as violent as a mass shooting.
“There are so many things that go into our moral decision-making,” he said.