Prisoners who are psychopaths lack the basic neurophysiological “hard-wiring” that enables them to care about other people, according to a new study.
“A marked lack of empathy is a hallmark characteristic of individuals with psychopathy,” said Jean Decety, Ph.D., a professor of psychology and psychiatry at the University of Chicago, who led the study.
Psychopathy affects approximately 1 percent of the general population in the U.S., but 20 percent to 30 percent of the prison population, according to the researcher.
For the study, the research team tested 80 prisoners between the ages of 18 and 50 who volunteered for the series of tests.
They were first tested for levels of psychopathy using standard measures. They were then studied with functional MRI technology, to determine their responses to a series of scenarios depicting people being intentionally hurt. They were also tested on their responses to seeing short videos of facial expressions showing pain.
“This is the first time that neural processes associated with empathic processing have been directly examined in individuals with psychopathy, especially in response to the perception of other people in pain or distress,” Decety said.
The prisoners in the high psychopathy group exhibited significantly less activation in the ventromedial prefrontal cortex, lateral orbitofrontal cortex, amygdala and periaqueductal gray parts of the brain, but more activity in the striatum and the insula when compared to control participants, the study found.
According to the researchers, the high response in the insula in psychopaths was unexpected, as this region is involved in emotion.
Conversely, the diminished response in the ventromedial prefrontal cortex and amygdala is consistent with what is already known about psychopathy, according to the researchers. This region is important for monitoring ongoing behavior, estimating consequences and incorporating emotional learning into moral decision-making. It also plays a role in empathic concern and valuing the well-being of others, they said.
“The neural response to distress of others, such as pain, is thought to reflect an aversive response in the observer that may act as a trigger to inhibit aggression or prompt motivation to help,” the researchers write in the paper. “Hence, examining the neural response of individuals with psychopathy as they view others being harmed or expressing pain is an effective probe into the neural processes underlying affective and empathy deficits in psychopathy.”
The study, supported with a $1.6 million grant from the National Institute of Mental Health, appears in the journal JAMA Psychiatry.
Source: University of Chicago