Psychopaths, with their superficial charms but lack of empathy, may act the way they do because their brains are wired to overvalue immediate rewards, a new study finds.
Psychopaths' brain wiring may also lead them to avoid thinking about the consequences of their potentially immoral actions, the study found.
Psychopaths are thought to make up about 1 percent of the general population and up to 25 percent of the prison population. Scientists who investigate psychopathy commonly define people with the disorder as having a lack of conscience or remorse, as well as impulsivity or a lack of self-control, shallow experiences of emotions, superficial charm and a grandiose sense of their own worth. [Understanding the 10 Most Destructive Human Behaviors]
More than three-quarters of incarcerated psychopaths are in prison because of a violent offense, according to a 2011 review of studies. Although not all psychopaths are violent, they can prove socially destructive in other ways, by lying, cheating and stealing, that review added.
"Psychopaths commit an astonishing amount of crime, and this crime is both devastating to victims and astronomically costly to society as a whole," Joshua Buckholtz, a neuroscientist and psychologist at Harvard University, said in a statement.
Scientific research into psychopathy "has for many years focused on emotion — in particular, this idea that psychopaths are cold-blooded super-predators who lack the ability to experience emotions," Buckholtz told Live Science. In the new study, the researchers wanted to focus more on psychopaths' behaviors.
"Regardless of what they feel, they engage in a lot of behavior marked by a lack of self-control, and we were interested in the neuroscience of that poor decision making," he said.
Buckholtz and his colleagues brought a mobile MRI scanner on a tractor trailer to a pair of medium-security prisons in Wisconsin. They scanned the brains of 49 inmates as the prisoners took part in a delayed gratification test that asked them to choose between two options — receiving a smaller amount of money immediately or a larger amount later. The researchers also had the inmates take a test to assess their level of psychopathy.
The researchers found that inmates who scored high for psychopathy showed greater activity in a brain region called the ventral striatum for the more immediate choice than those who scored lower in psychopathy. Previous studies suggested that the ventral striatum is linked with the ability to evaluate the value of different choices.
In addition, the scientists found that in psychopaths, the connection between the ventral striatum and another brain region known as the ventral medial prefrontal cortex were much weaker than normal. Prior work suggested that the ventral medial prefrontal cortex "is important for 'mental time travel' — that is, thinking about the future consequences of actions," Buckholtz said. [10 Things You Didn't Know About the Brain]
These findings suggest that psychopaths often behave antisocially because their brains are wired in a way that makes them both overvalue immediate rewards and neglect the future costs of potentially immoral actions. In fact, the more abnormal inmates' brains were in both of these regards, the more crimes the prisoners were convicted of.
"The pattern of decision making we see in psychopathic individuals is not all that different from that in people with other kinds of self-destructive behavior, such as substance abusers, compulsive over-eaters or compulsive gamblers," Buckholtz said. "Whatever else may be going in psychopathy, such as deficits of emotion, our findings put psychopathy in the sphere of things that can be intervened in."
Future research can investigate whether there may be ways to help psychopaths improve their thinking about the future, such as through behavioral therapies or noninvasive brain stimulation, Buckholtz said.
The scientists detailed their findings online today (July 5) in the journal Neuron.
Original article on Live Science.