People with psychopathic tendencies—who may constitute upwards of 15 percent of prison populations—poorly activate parts of the brain responsible for empathy, according to a study in the April 24 JAMA Psychiatry online. While control subjects cringe when they see a person in pain, as when getting a hand slammed in a car door, prisoners who scored high on a test for psychopathy demonstrated little empathy. Functional magnetic resonance imaging of the brain indicated that those individuals also had subpar function in the orbital frontal circuit, which helps process emotions. Notably, some of the same brain areas are compromised in frontotemporal dementia (FTD). People with FTD may flout social norms and land in hot water. However, study senior author Kent Kiehl of the University of New Mexico in Albuquerque said he has seen no evidence that people with FTD are more likely to end up in the prison system as those with psychopathy are prone to do.
Psychopathy, which is present in less than 1 percent of the general population, classically manifests as lack of empathy, among other symptoms. To identify defects in the empathy-processing circuitry of psychopaths, Kiehl, who travels with a mobile MRI scanner to study psychopathy on prison grounds, collaborated with first author Jean Decety of the University of Chicago, Illinois. The researchers applied a standard rating scale to classify 80 volunteer prisoners as having a high, medium, or low level of psychopathy. Then they used functional MRI to measure blood flow in the brain while the participants looked at video clips and pictures. Some imagery depicted painful experiences, or faces with expressions of discomfort. Others were neutral. For example, a neutral stimulus of a person hitting a ball with a bat might contrast with a pain image of a person hitting another person with a bat, Kiehl said.
The researchers asked the participants if the people in the pictures felt pain. While those who scored high for psychopathy could correctly identify when that was true, their MRIs differentiated them from people with proper empathy. The high scorers had less activation in the orbital frontal circuit, Kiehl said. “It suggests that perhaps there are real physiological correlates for people with [psychopathy],” said Bruce Miller of the University of California, San Francisco, who was not involved in the study. “It makes sense that this system would be hypoactive in people who are cruel to others.” The people who scored high for psychopathy also had higher activity in the insula. This area is also thought to be involved in processing pain, emotion, and empathy, although it is apparently not required to experience those feelings (Damasio et al., 2013). The implications of the insula finding are uncertain, Kiehl said.
By identifying the scene of the crime, so to speak, Kiehl hopes to come up with methods to help people with psychopathic tendencies control their behavior and avoid incarceration. Several study participants have expressed interest in treatments that would keep them out of prison, Kiehl said. While pharmaceuticals are a possible avenue, Kiehl is focusing his current efforts on brain-training therapy. Just as practice can keep cognitive functions like memory strong (see ARF related news story), he hopes it will be possible to train people to respond to the cues that someone feels pain or fear, and behave appropriately.
Research on people with psychopathy has the potential to inform studies of FTD, and vice versa, Kiehl suggested. Both conditions involve defects in the uncinate fasciculus, the white matter bridge that links the frontal and temporal lobes, he said. Kiehl and colleagues have shown that this connection is shrunken and weakened in psychopaths (Motzkin et al., 2011), and it can also degenerate in FTD, he said.
The lack of empathy in Kiehl’s subjects most resembles that seen in people with degeneration of the right temporal lobe, Miller said (Rankin et al., 2006; Eslinger et al., 2011). They often exhibit loss of empathy, while FTD patients who have left-brain degeneration are more likely to have language difficulties (Mychack et al., 2001). Kiehl also found that the deficits in the uncinate fasciculus were somewhat more severe on the right side of the brain of people with psychopathy.
However, there are important differences between FTD and psychopathy. “It is very difficult to make an inference from this study about FTD,” cautioned Martin Rossor of University College London, U.K., in an e-mail to Alzforum. Poor empathy is no indication of degenerative FTD, wrote Rossor, who was not involved in the JAMA Psychiatry study. One difference is that the overall physiology of psychopathy is typically bilateral, despite the minor increase in uncinate fasciculus defects on the right side of the brain.
Case reports indicate that people with FTD can certainly run afoul of the law (Mendez, 2010). However, Kiehl, who has worked in prisons for two decades, said he has seen no evidence that people with major dementia are incarcerated. After acting out, they are more likely to find themselves in secure care facilities due to the nature of their condition, he said.
In addition, any unlawful acts by people with FTD are hardly the callous crimes for which people with psychopathy are convicted, Miller said. “The crimes [people with FTD] commit are often silly and motivated by instant desire,” he said. They might steal a sandwich simply because they are hungry, or commit a hit-and-run when they cannot be bothered to pull over. While they know their actions are wrong, they do them anyway.
Another distinction is that FTD symptoms are acquired late in age. In contrast, Kiehl has met psychopaths who say their indifference to others’ feelings existed since childhood. Genetic studies suggest psychopathy is probably about 50 percent based on inherited factors, Kiehl said. A predisposition toward psychopathy, plus environmental factors, could lead to the psychopathy, he suggested. For example, being abused as a child has been linked to psychopathy later in life (reviewed in McCrory et al., 2012). Kiehl has collected DNA from his subjects, but has yet to publish any of the analysis. The number one genetic risk factor for violent behavior, he noted, is the Y chromosome.
Decety J, Skelly LR, Kiehl KA. Brain response to empathy-eliciting scenarios involving pain in incarcerated individuals with psychopathy. JAMA Psychiatry. 2013 Apr 24. Abstract
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