Decoding the Neural Pathway from Psychopathy to Serial Murder

News stories of serial killings are, unfortunately, common. And almost always, there is no apparent motive behind the bloodbath. It makes you wonder if the serial killer is wired differently from the rest of us. What makes a person kill another human being in cold blood? Is it in the genes, or do dysfunctional and abusive families breed serial killers? Is there an “urge to kill” that serial killers cannot resist?

In his book The Criminal Man, published back in 1911, Cesare Lombroso argued that a significant proportion of all criminals are characterized by distinctive physical and anatomical features and these people are, therefore, born to be criminals.

The theory of Lombroso was based, in a significant degree, on the results of his medical and anatomical examinations of criminals. However, his observations were mostly descriptive and were not supported by any statistical data and proper population analysis. Later researchers who addressed this question (for instance, Goring in his The English convict: a statistical study, 1913) found no evidences in support of Lombroso’s conclusions. The statistical data, however, did not put the matter at rest, and various researchers were revisiting the idea of hereditary predisposition to criminality in the course of 20th century.

The question of “nature or nurture” in regards to the excessive level of cruelty in some individuals still have no clear answer. However, scientists have found that, contrary to popular belief, not all serial killers have abusive childhoods. Also, most serial killers exhibit the neurological traits of criminal psychopathy and have different brain chemistry than individuals who show no psychopathic tendencies.

Inside the Brain of a Criminal Psychopath

Many researchers believe that most serial killers show one or more singular traits of psychopathy, such as a tendency to manipulate others, superficial charm, abnormal egocentricity, and lack of empathy that shows up as guiltlessness. Most of them also exhibit anti-social traits like impulsive behavior and aggression. However, not all psychopaths go on to become serial killers.

Several studies have established the neurological roots of anti-social tendencies, violent behavior, and psychopathy.

According to one study, psychopaths show impaired connectivity between the ventromedial prefrontal cortex (vmPFC) and the amygdala and also between the vmPFC and the medial parietal cortex and reduced white matter in the right uncinate fasciculus that connects the vmPFC with the anterior temporal lobe. Incidentally, the amygdala processes negative stimuli while the vmPFC interprets the signals sent by the amygdala. The circuitry in the vmPFC region has been found to be associated with personal moral judgment.

In a study on patients with lesions in this region of their brains, it was found that these individuals tend to view personal moral violations as more acceptable than the subjects with healthy brains. The former group also tends to be bothered less by personal moral dilemmas. This indicates that the vmPFC region plays a crucial role in triggering inward-looking and reflective emotional reactions that influence moral choices. When the neural circuitry in this region is faulty, the individual does not feel any bothersome negative emotion when faced with negative stimulus. This probably explains why serial killers remain aloof to the cries of distress by or the sight of pain in their victims and also the lack of guilt at their doings.

In this context, it must be clarified that the above-mentioned impairment in the psychopath’s brain does not render him incapable of distinguishing between right and wrong. Research has uncovered that psychopaths understand what is right and what is not; they are just not bothered by the consequences that may arise from behaving inappropriately.

Few years ago, one study has uncovered a genetic basis for the impaired neural circuitry in the vmPFC region. According to this study, the presence of a particular variation of the monoamine oxidase A gene leads to a reduction in the mass of the vmPFC and amygdala regions. So it seems that genetics also has a role to play in determining whether a person will go on to kill another one when provoked or merely utter a few cuss words.

Age and Criminal Psychopathy

The role of the vmPFC in triggering psychopathic behavior and a propensity to kill has also thrown up an interesting discussion in the legal community. The vmPFC continues to mature till the age of 25. This indicates that juvenile offenders actually have little control over how their brains make them act. So it is no surprise that a survey in Britain found that more violent crimes are committed by individuals aged between 16 and 24 years than by all the people in other age groups taken together. In countries where the death penalty is prevalent, there is a debate whether lawmakers and judges should consider neuroscientific evidence before delivering death sentence in particular cases.

Co-Morbidity of Psychopathy and Other Mental Illnesses

Several scientists also associate mental conditions like Borderline Personality Disorder (BPD) and schizophrenia with serial killing. Their belief is based on numerous worldwide findings that a high percentage of prisoners convicted of committing violent crimes suffer from some sort of a mental illness. Some other surveys show that head injuries and birth complications that result in neurological damage are common amongst death-row convicts.

According to one study, there is a high level of co-occurrence of schizophrenia and psychopathy in forensic patients. Schizophrenic patients and those with high psychopathic scores exhibited low amygdala arousal when they were shown fearful faces. This means that these individuals cannot recognize fear in others and respond compassionately.

Scientists also see a connection between psychopathic symptoms and BPD. Persons afflicted with BPD are emotionally unstable and are prone to anxiety and impulsive aggression. What is more, those suffering from BPD are believed to have low or no empathy, a quality that lets a person be considerate and compassionate to the pain of others. On the other hand, psychopaths are known to be pathologically egocentric that makes them insensitive to the needs and pain of others. Scientists believe that BPD and psychopathy have common neural bases.

These findings raise new debates within the legal and medical circles. Many believe that this bank of neurological evidence should be taken into consideration before delivering punishment to serial killers. Counselors, psychologists, and therapists in institutions where violent criminals are lodged should also be made aware of findings like the co-morbidity of psychopathy and certain mental illnesses, so they can devise the most effective therapy that optimizes the chances of rehabilitation of serial killers and other violent offenders.

Because the propensity to go on a killing spree springs from psychopathy, an established and well-researched mental condition, both society and the legal machinery should take into account the neurological findings before judging legally or morally.


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Image via Igor Stevanovic / Shutterstock.

Viatcheslav Wlassoff, PhD

Viatcheslav Wlassoff, PhD, is a scientific and medical consultant with experience in pharmaceutical and genetic research. He has an extensive publication history on various topics related to medical sciences. He worked at several leading academic institutions around the globe (Cambridge University (UK), University of New South Wales (Australia), National Institute of Genetics (Japan). Dr. Wlassoff runs consulting service specialized on preparation of scientific publications, medical and scientific writing and editing (Scientific Biomedical Consulting Services).
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