Serial killers exert a particular fascination in our culture, despite the apparent revulsion. Stereotypically, a serial killer lacks empathy, guilt, and shame. However, modern neuroscience has elucidated the neurological basis of these traits.
At the University of Chicago, researchers imaged the brains of 800 individuals incarcerated for homicide. They found startling evidence of reduced grey matter compared with other offenders. According to their analysis, these reductions are associated with impaired emotional processing, behavioral control, and social cognition.
Nevertheless, few serial killers meet the diagnostic criteria necessary to qualify as insane. The majority display signs of psychopathy or sociopathy, and many meet the criteria for antisocial personality disorder.
Psychopathy and sociopathy both involve blunted affective responses, disregard for norms, and difficulty controlling behavior. Some of these behaviors appear to be rooted in childhood trauma, but some result from brain abnormalities.
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Recent research has shown that killers have decreased the amygdala and frontal cortex interconnection. Normally, the amygdala processes emotional information, such as fear. Dampened connections between the amygdala and prefrontal cortex impair their ability to socialize.
Decreased communication between the ventromedial prefrontal cortex and the amygdala is also common. The vmPFC has been implicated in personal moral judgment in previous studies. In a similar study, scientists studied patients with lesions in this brain region. They discovered the subject was more likely to view moral violations as acceptable.
When vmPFC circuitry is damaged, it impairs an individual’s ability to perform reflective emotional processing. Consequently, they do not feel as bothered by negative stimuli. This could be the neurological underpinnings of a killer’s aloofness.
On the other hand, some research shows that killers understand the difference between right and wrong. Yet, they do not worry about the consequences that may arise from murderous behaviors.
Schizophrenics and psychopaths typically underperform in studies examining their response to fearful stimuli. When shown fearful faces, a healthy brain responds by emulating the fear. Serial killers lack this empathetic response, impairing their ability to be compassionate.
Damaged prefrontal cortex circuits also affect a person’s impulse control. Therefore, serial killers may struggle to control impulsive tendencies, making them more aggressive. Psychopaths also demonstrate higher levels of egocentricity, decreasing their sensitivity to the needs of others.
Even more worrisome, serial killers possess a strengthened emotional drive to harm and kill others. Early childhood trauma may lead serial killers to dissociate from their victims. In many cases, convicted murderers report significant abuse at the hands of their parents.
Traumatic experiences can lead to long-term alterations in brain connectivity. Thus, a childhood filled with abusive parents could cultivate a killer unintentionally.
Inadequate inhibition of the nucleus acumens may exacerbate impulsivity. Unfortunately, atrophied prefrontal cortexes often fail to inhibit this brain region. Furthermore, traumatized individuals showcase classic signs of atrophy in their prefrontal cortex.
Co-morbidity of borderline personality disorder, schizophrenia, and associated antisocial disorders confound results. Nonetheless, it is evident that many serial killers share abnormal neurological structures. Additionally, schizophrenia with co-morbid alcoholism increases the risk of becoming a killer by 17-fold.
Currently, more research is needed to fully elucidate the connection between someone’s brain and their likelihood of becoming a killer.