The argument over whether genetics or environment plays the most important role in in a person’s development has long been a topic of passionate debate in the field of psychology. The concept of “nature versus nurture” was popularized during the Victorian era by Francis Galton, the father of modern genetics and half-cousin of Charles Darwin. While this popular expression is still used to spark discussion about “acquisition versus heredity,” nowadays, most scientists generally agree that both affect and influence the other constantly.
A growing body of research about the genetic contribution to the condition of sociopathy/psychopathy suggests that there are indeed anatomical correlates that differentiate a violent offender’s brain from that of a “normal” brain. The most recent edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5, 2013) does not recognize sociopathy or psychopathy as official diagnoses, but rather categorizes those who exhibit socially aberrant behavior as suffering from antisocial personality disorder. Typically characterized by lack of impulse control, empathy, morality and guilt, what we commonly to refer to as “psychopathic” or “sociopathic” behavior can actually be identified in the brain scans of individuals who possess these traits.
Several areas of the brain are engaged in regulating emotions, impulses, morality and aggression, including the amygdala, the cerebral cortex, and the frontal lobe. Sociopaths/psychopaths typically possess significantly less grey matter in both the anterior rostral prefrontal cortex and the temporal poles. Such structural abnormalities are often accompanied by a lower rate of brain activity in these critical areas, resulting in disproportionate egocentric or manipulative tendencies.
In addition to the visible anatomical differences that can be easily seen in brain scans, scientists have also identified mutations in specific genes that are associated with a predisposition for violence. Chief among these is MAOA-L, a mutation of MAOA (monoamine oxidase) that is expressed at a lower rate and linked to an increased risk of violent or aggressive behavior. MAOA-L was first connected to aggressive behavior in 1993, and is commonly referred to as the “warrior gene.” In its unadulterated form, MAOA effectively breaks down certain neurotransmitters (chemicals that the body uses to control its functions) in the brain that are associated with aggression. The mutated version, MAOA-L, inhibits this process, resulting in an excess of these chemicals, thereby increasing the potential for expression of violent or compulsive behavior. A mutation in a gene called CDH13 (which has previously been associated with ADHD and alcoholism) has also been shown to have an association with undesirable social behaviors. Predictably, criminals who possess both of these mutations are more likely to be violent repeat offenders.
Dr. Nigel Blackwood of King’s College in London recently published a study that analyzed the MRI scans of forty-four violent adult male offenders in Britain who had previously been diagnosed with antisocial personality disorders. He confirmed that psychopaths’ brains are indeed different from regular offenders, stating that, “Regular criminals are hyper-sensitive to threat, quick tempered and aggressive, while psychopaths have a very low response to threats, are cold and their aggressive behavior is premeditated.” He characterized psychopaths as “cold hearted,” and other violent offenders as “hot blooded.”
It is estimated that psychopaths make up one percent of the population, but that a trifecta of variables is generally present in those who act out violently. Brains that are anatomically deficient of grey matter in the aforementioned key areas, genetic mutations and abuse or violence inflicted during childhood are three ingredients that can create a perfect storm in which a violent sociopath or psychopath can develop. While there are certainly cases where the first two variables occur without the addition of violence, even children with pristine childhoods are at risk of developing antisocial behavior, so the liability must be managed. Given that the “nature” of brain structure and genetics are largely immutable, the “nurture” portion of the equation becomes very important. Some parents who suspect that genetic factors are at play have been able to overcome them by compensating with positive home environments and creative and/or physical outlets (hobbies, sports, etc.). Childhood intervention appears to be critical in avoiding the potential pitfalls of physiology and genetics. Because young brains are still “plastic” and can be structurally altered up to a point, this time period offers the most potential when it comes to making positive modifications.
Because these individuals are unable to grasp the concept of punishment, they typically do not benefit from rehabilitation programs. One school in the United Kingdom tasked with educating children who have emotional and behavioral problems is implementing a rewards based system that shows great promise. While an actual “cure” may prove elusive, the immediate goal is to get the troubled kids to learn how to transform selfish inclinations into positive responses and activities.
Renowned neuroscientist Dr. James Fallon was already an expert at identifying the brains of murderers and serial killers when, upon examining his own brain scan, he discovered that he possessed brain anatomy featuring the same hallmark characteristics of his violent subjects. Listen to this week’s episode of Weekly Infusion podcast to find out how he became a successful scholar, writer, biotechnologist, husband and father – in spite of his brain’s physiology.