Predisposed to Kill: The emerging field of neurocriminology

Michael is a happily married man who loves his wife and his stepdaughter. He has no prior history of criminal or violent behavior. Without explanation, he suddenly becomes aggressive and his bedtime rituals with his prepubescent stepdaughter become sordid. He eventually gets into bed with her. Before he was due to be transported to prison, he visits the hospital. He makes lewd remarks towards the nurses and urinates publicly. An astute neurologist orders an MRI, which reveals a tumor growing at the base of the orbitofrontal cortex - an area of the brain responsible for inhibition.  After the tumor is resected, he returns to normal and reunites with his family. Yet a prickly question surfaces: Is Michael really responsible for his inappropriate sexual advances? At the intersection of brain pathology and deviant behavior, a bold new field emerges: neurocriminology, which uses the latest neuroscience research to predict, prevent and ultimately punish criminal behavior. 

                           Michael's brain MRI showing tumor in the orbitofrontal cortex.

                           Michael's brain MRI showing tumor in the orbitofrontal cortex.

In the 2002 Steven Spielberg film Minority Report a special police unit uses humans with precognition powers, or precogs, to prevent crimes before they happen.  The neuroscience of precognition would be an incredible topic to breach. This isn’t that. However,  


A number of studies point to specific biological factors, such as hormone levels, neurotransmitter levels, physiological indices or brain impairments which are predictive of future offending. 

Prediction of crime

In order to play the role of a precog, we must first understand what the mind of a criminal looks like.

 Component 1: Genetics

Jeffrey is an adopted boy in a loving middle class family.  Yet he is troubled from the beginning: He begins drinking alcohol at 10 years old, is arrested for burglary at 11, abuses drugs as a teenager and kills his first victim at 20.  He escapes from prison and after killing another is then sentenced to death. While in prison, an inmate notices a striking resemblance between him a man he met in another prison. As it turns out, that man was his biological father, also an institutionalized criminal.  His grandfather also killed two people and was a notorious bootlegger. 


This case, along with an impressive amount of findings unequivocally documents the heritability of aggression between 40-60%. 

A powerful genetic predisposition is only the beginning. Let’s say the mother of said future delinquent smokes, washes down an unhealthy meal with small amounts of alcohol or accidentally ingests lead. The chances of fetal brain malformation and subsequent increase in antisocial behavior are 2.5-fold.

Component 2: Hormones and neurotransmitters

Now let’s suppose the reason the mother engages in unhealthy behavior is due to stress. 


Psychological stress at various stages during development may produce lasting changes in HPA axis functioning and thereby predispose an individual to antisocial behavior. 

The HPA axis, or hypothalamus-pituitary-adrenal axis, regulates the body’s stress response and the release of the hormone cortisol.  Low levels of cortisol in childhood are predictive of aggressive behavior 5 years later, in adolescence. In addition, high testosterone and low serotonin levels are both markers of people who show impulsive and aggressive behavior.  

Assembly: Neuroimaging

The structural pieces are now in place to erect the criminal brain.  The result? An individual who lacks proper activation in areas responsible for attention, impulse-control, emotion processing and decision-making.  But just like Michael’s case, the same brain areas can be negatively affected as a result of a tumor, or in some cases - physical insult later in life.


Neurological patients who had suffered from an accidental head injury to the ventral prefrontal cortex show poor decision-making, reduced autonomic reactivity to socially meaningful stimuli and psychopathic-like behavior. 

To note, most brain imaging studies are essentially correlational and cross-sectional, and cannot definitively prove causality. Longitudinal and case studies can, however, be predictive of causality yet not many have been conducted.

Prevention of Crime

A word of warning. Just because there is robust evidence a criminal mind has certain irrefutable characteristics, social and environmental perspectives shouldn’t be ignored. A mere predisposition for criminal behavior cannot be reduced to one or two brain circuits or hormone levels.  This precog thing is challenging. Future research should address the sophistication of these networks and try to understand how they interact and adapt to the environment.  


If neurocriminology can identify replicable biological risk factors that provide incremental knowledge over and above the traditional variables that are currently used in in dangerousness assessments, this would further aid violence prediction.

With the available evidence, options for prevention include psychopharmacological interventions to treat hyperactivity and depression conditions which exist in tandem with aggressive behavior.  More ethical alternatives include nutritional supplementation such as omega-3 fatty acids and exercise regimes or transcranial direct stimulation (TDS) and mindfulness training. 

Punishing the Crime  

What about apprehending and actually judging the mind of someone who committed an immoral act? The moral circuitry board of the brain is equal in complexity to the topic breached. 

  A schematic diagram of brain regions that are activated only in moral decision making (green), regions that are impaired only in antisocial groups (red), and regions common to both antisocial behaviour and moral decision making (yellow). This overlap gives rise to the ‘neuromoral’ hypothesis of antisocial behaviour, which states that some of the brain impairments that are observed in antisocial individuals disrupt moral emotion and/or decision making, thereby predisposing individuals to rule-breaking, antisocial behaviour. 

 

A schematic diagram of brain regions that are activated only in moral decision making (green), regions that are impaired only in antisocial groups (red), and regions common to both antisocial behaviour and moral decision making (yellow). This overlap gives rise to the ‘neuromoral’ hypothesis of antisocial behaviour, which states that some of the brain impairments that are observed in antisocial individuals disrupt moral emotion and/or decision making, thereby predisposing individuals to rule-breaking, antisocial behaviour. 

While most violent offenders admit the act they committed was wrong, the compelling question that emerges is: Do they feel that it’s wrong? Moral decision-making is deeply influenced by emotion, and the amygdala, the engine that drives decisions in the wrong (or right) directions, needs some repair in individuals with aggressive behavior.  


So if the criminal can’t feel it’s wrong, are they still responsible for the crime?

This affective metric could be entered as a mitigating factor in the punishment of an offender (similar to low IQ) in order to establish the rational capacity of the person.  Given the strong evidence Michael’s actions were driven by the tumor in his brain, is he still responsible for his vulgar behavior? 

Currently in the United States, an individual is deemed “responsible” for their actions if two conditions are met. 1. They have sufficient rational capacity and 2. They are not acting under coercion. Rational capacity is typically interpreted as whether the individual knew what he or she was doing. Michael admitted that “somewhere deep deep in the back of my head, there as a little voice saying, ‘you shouldn’t do this.’” Michael knew he was wrong. And in the eyes of the law, Michael was guilty.

The causal flow of Michael’s case was easy.  He was normal; he had a brain tumor and had pedophilic interests, had tumor removed, became normal again. The majority of cases are much more complex since the biological risk factors for offending will never be known prior to the crime committed.


As the law currently stands in the US and other countries, the documentation of neurobiological risk factors, no matter how early they originated, does not render that individual lacking responsibility. 

Does this mean the law needs revision to incorporate the increasing evidence that neurobiological factors contribute to psychopathic traits? Perhaps. The judicial system in the US sees defendants as guilty or innocent, categorically.  While some risk factors associated with criminal violence are also categorical (brain injury or tumor), some are dimensional: degree of prefrontal dysfunction or level of a certain hormone.  In making a decision of blameworthiness, shouldn’t neurobiological and genetic influences combined with social influences be taken into account?

Although cognitive intelligence is the benchmark used by the law to document the capacity for rationality, the new fields of affective neuroscience are providing us with evidence that emotion informs decision making – a finding that is not yet instantiated in the law.

There is no longer any reasonable doubt that a criminal mind is strikingly different.  The current research raises the question of whether the law will reformulate its current, long-standing concept of responsibility and implement a system which judges the entire psychological persona, and not just a fragment.  

ResearchBlogging.org Glenn AL, & Raine A (2014). Neurocriminology: implications for the punishment, prediction and prevention of criminal behaviour. Nature reviews. Neuroscience, 15 (1), 54-63 PMID: 24326688