What drives psychopaths to commit violent crimes or immoral actions could have a lot to do with how their brains are wired to make decisions, a new study finds.

Traditionally, scientists have seen psychopaths as “these cold-blooded, emotionless predators” who “do all of these terrible, terrible things because they don’t feel emotions” like the rest of us do, said Joshua Buckholtz, co-author of the study and assistant professor of psychology at Harvard University.

The new study, published July 5 in the journal Neuron, suggests the problem may not simply be their emotional capacity.

Buckholtz and his co-authors drove an MRI scanner to Wisconsin to study the incarcerated population in two medium-security prisons there. While only about 1 percent of the general population is thought to meet the criteria for psychopathy, 15 to 25 percent of the male prison population in North America apparently does, according to an estimate from the National Library of Medicine.

The team, which included researchers from the University of Wisconsin-Madison and the University of New Mexico, scanned the brains of 49 volunteer inmates while the prisoners performed a delayed-gratification test. The scans of those inmates who scored higher on the gold standard assessment for psychopathy showed more activity in the ventral striatum region of the brain. (The researchers controlled for age and substance abuse history.)

The ventral striatum helps the brain weigh the value of different decisions. It’s driven by immediate rewards, with less concern for the long term.

Once the ventral striatum-psychopathy connection was identified, the next step was examining why the two might be linked.

“We know that the brain is networked,” Buckholtz said. “Individual regions don’t work in isolation, and there are lots of really exquisite and nuanced patterns of regulatory control all throughout the brain.”

Researchers mapped the connections between the ventral striatum and other regions of the brain, and found that inmates with higher levels of psychopathy had weaker connections between the ventral striatum and the prefrontal cortex.

The prefrontal cortex is associated with decision-making focused on the future.

Those two results together, Buckholtz said, suggest that psychopaths have “something of a broken regulatory circuit.”

How to treat psychopaths

Better understanding of how psychopaths’ brains work could pave the way for better treatments. In particular, approaches to addressing other disorders characterized by impulsive decision-making might be worth a look.

For example, the ventral striatum is also overactive when people with substance use disorder are exposed to drug stimuli. Strategies aimed at changing their behavior could potentially be applied to psychopaths as well, Buckholtz said.

Most of all, however, he hopes the study will help change the way we think about psychopathy.

“Their bad decisions, the bad choices that they make, are entirely predictable given how their brain is wired,” Buckholtz said.