Wired for Crime? How Brain Differences Shape Criminal Behavior.

Introduction

Why do some people choose to break the law while others, in similar circumstances, do not? The answer may lie deep within the human brain. Emerging research suggests that specific brain abnormalities neurologically wire certain individuals to engage in criminal behavior, increasing the likelihood of impulsive and violent actions [1]. Understanding the science behind this dark side of human nature reveals that biological factors play a role in influencing criminal tendencies. Nevertheless, how much of our behavior is dictated by the brain, and what implications does this have for the justice system and rehabilitation of known criminals? The answers to these questions could reshape our approach to crime and punishment.

Background

The brain’s development is a complex process involving interconnected systems. These systems, alongside environmental, neurological, and psychiatric factors, enable basic tasks and higher cognitive functions, like attention and language [2]. No single brain structure operates in isolation; each region plays a distinct role in shaping behavior. This interconnectedness becomes apparent in criminal behavior, where regions governing impulse control, emotions, and decision-making are often implicated [2].

The story of Phineas Gage remains one of the most well-documented cases in neuroscience. On September 13, 1848, Gage, a railroad foreman, was packing material onto blasting powder when it exploded, shooting a tamping iron through his cheek and into his brain. Gage survived but showed drastic changes after the incident. Gage’s colleagues initially described him as “[their] most capable and efficient foreman, one with a well-balanced mind, and who was looked on as a shrewd smart businessman.” Afterward, he became “fitful, irreverent, and grossly profane” [3]. These shifts, later attributed to prefrontal cortex damage, demonstrated the brain’s role in shaping personality and behavior.

Studies of psychopathy and its connection to criminal actions further illuminate this relationship. As seen in Gage’s case, damage to the prefrontal cortex caused drastic behavioral changes, and psychopathy similarly involves dysfunctions in brain regions involved in emotional regulation and impulse control. Psychopathy, characterized by traits such as lack of remorse, emotional detachment, and impulsivity, is highly prevalent in criminal populations [4]. Of the approximately 6.7 million adult males in the United States involved in the criminal justice system—whether in prison, jail, parole, or probation—16% are psychopaths [4]. These traits are strikingly similar to the behaviors Gage exhibited after his injury, highlighting how damage or dysfunction in the brain can lead to profound shifts in personality and behavior, offering a clearer understanding of how neurological factors can contribute to criminal tendencies.

The Menendez Brothers and the Amygdala

Discussions of psychopathic behavior often cite the high-profile case of the Menendez brothers, Lyle and Erik, criminals convicted of murdering their parents in 1989. What distinguishes this case is the alleged motivation behind the crime. The brothers claimed that they endured years of sexual abuse by their father, starting from when they were as young as six years old. Their older cousin confirmed these claims during the first trial, saying “that Lyle told her he was too scared to sleep in his room because his father would come in and touch his genitals.” This disturbing testimony demonstrates the brothers’ potential motive behind their actions [5]. 

The amygdala, a key brain region that processes emotions and assigns emotional values to different stimuli, guides appropriate behavioral responses [2]. When individuals encounter negative or threatening situations, the amygdala activates, releasing adrenaline and cortisol and triggering responses such as fear, anxiety, or heightened alertness. However, in individuals who have experienced early childhood trauma, the amygdala may become hypersensitive. This response can lead to stronger emotional reactions to stimuli that resemble past traumatic experiences, even when there is no real threat in the present situation [6]. The Menendez brothers claimed that their father’s abuse had escalated to the point where they feared for their lives. Hyperactivity in the amygdala could have amplified their fear, leading them to perceive their father as an immediate threat and contributing to their decision to commit the murders as an act of self-defense.

Donta Page and the Prefrontal Cortex

The case of Donta Page is a well-known example of how neurological evidence can influence a criminal’s sentencing, in this case, allowing the individual to avoid the death penalty. In 1999, Page robbed, raped, and brutally murdered a woman named Peyton Tuthill. Although he was initially a strong candidate for the death penalty, his defense team presented compelling evidence of his brain pathology, which dramatically shifted the outcome of the case. A comparison of the defendant’s brain scan with an average of 56 healthy control subjects revealed reduced activity in the prefrontal cortex’s ventrolateral, ventromedial, and polar regions. Researchers linked this dysfunction to a series of severe traumas from his childhood, including chronic abuse, early head injuries, and lead exposure [7]. 

In the following court case, the defense explained that Page’s brain dysfunction impaired his decision-making, reduced self-awareness, detached him emotionally, and weakened his  behavioral control. This argument highlighted the role of the prefrontal cortex, located directly behind the forehead, which is crucial in guiding human behavior through mechanisms that regulate thoughts, emotions, and actions [8]. It is also responsible for higher-level decision-making, impulse control, emotional regulation, and predicting consequences [9]. Damage or dysfunction to the prefrontal cortex increases the likelihood of engaging in criminal behavior [2].

In a study by Bechara et al. (2000), patients with bilateral lesions to their ventromedial prefrontal cortex (VMPC) experienced significant difficulties in personal and social decision-making. Patients with VM lesions often preferred what provided them “with high immediate reward to those with smaller reward, although those with small reward were more advantageous in the long term” [1]. So, when presented with an opportunity to obtain something valuable, such as money, drugs, or other incentives, those with prefrontal lobe damage may act impulsively and fail to consider the potential harm to others or the legal consequences. This diminished capacity for self-restraint makes it more difficult for them to adhere to societal norms, increasing the likelihood of criminal behavior. In Page’s case, the defense argued that these impairments reduced his guilt, resulting in a life sentence rather than the death penalty [7]. 

Additional Case Studies

There is a lack of research exploring the potential brain abnormalities associated with criminal behavior. However, numerous hypotheses suggest connections between historical and contemporary criminals and the underlying neurological issues linked to their actions. Richard Ramirez, known as the “Night Stalker,” endured severe childhood physical abuse and suffered brain injuries at the ages of two and five. Courts later convicted Ramirez of murdering and raping at least 13 individuals [10]. Similarly, authorities convicted Albert Fish of killing three children and several infants, and he had endured a significant head injury during his teenage years [11]. David Berkowitz experienced at least three serious accidents as a child, including being struck by a car. Later on in his adult life, he became increasingly withdrawn and antisocial. He ultimately murdered six people and injured seven others [12]. These examples highlight a concerning pattern: many criminals have experienced some form of traumatic brain injury (TBI) or abuse during their formative years. Notably, “researchers estimate that up to 60% of incarcerated individuals are living with TBI in our prisons” [13]. Despite this, neuroimaging and its implications for understanding criminal behavior are rarely considered in court cases, raising important questions about the intersection of neuroscience and the legal system.

Link to Criminal Justice System

A study found that “73% of prisoners convicted of violent crimes had frontal lobe damage (FLD), while only 28% of those who committed non-violent crimes had FLD” [14] This highlights the strong link between brain dysfunction and criminal behavior, emphasizing the need for targeted reforms.

Individuals with brain abnormalities benefit from correctional facilities rather than traditional prisons, as their actions may stem from impaired cognitive functions, impulsivity, or judgment issues. Traditional prisons focus primarily on punishment and containment, which may not address the underlying neurological issues driving their behavior. Correctional facilities and programs, on the other hand, can provide specialized treatment, rehabilitation, and therapy designed to improve their mental health and cognitive abilities. For example, the TBI In Corrections project, born in 2014, works to develop a screening tool for incarcerated individuals with a history of brain injury [15]. Their goal is to identify those who would benefit from the aforementioned additional services. This approach may help offenders recover, manage their conditions, and reduce the likelihood of reoffending, promoting a criminal justice system that considers the root causes of criminal behavior. 

Conclusion

Multiple case studies show how brain abnormalities and imbalances, such as dysfunctions in areas controlling impulse regulation and aggression, can increase the likelihood of criminal behavior. This idea challenges traditional views of accountability in the justice system, encouraging a shift toward rehabilitation programs like the TBI In Corrections project that address these neurological factors. 

References

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