Psychopathy is classed as an anti-social personality disorder, but could there be a difference in a psychopath’s brain that leads to psychopathic behaviour?

When it comes to some of the most heinous acts of violence in human history, psychopaths are often to blame. We portray psychopaths in the media as cold-blooded, evil monsters who lack empathy. In the past, experts have always believed that psychopathic behaviour is a set of personality traits, that psychopaths make choices that ruin other people’s lives.

But now, studies are showing that a psychopath’s brain is different from a normal person’s one.

“Because it’s the choices of psychopaths that cause so much trouble, we’ve been trying to understand what goes on in their brains when they make decisions that involve trade-offs between the costs and benefits of action.” Joshua Buckholtz – study author

Psychopaths have fascinated us ever since the term was first coined. Despite the fact that they represent a small percentage of society, they commit the most crimes. It is this anomaly that has led to studies of psychopath’s brains. It’s that old nature versus nurture debate.

Most experts believe it is a complex mix of the two, however, as new brain imaging becomes available, it is looking increasingly likely that a psychopath’s brain is different from a normal person’s brain. So how is it different?

Studies of the Brains of Psychopaths

One study examined the differences in brains of criminals who were incarcerated after committing the worse kinds of criminal acts. Before the study, the prisoners completed the Hare Psychopathic Checklist. This is the industry standard test which asks questions to determine whether a person has psychopathic tendencies.

Another study scanned the brains of prisoners who had high scores for psychopathy on the same checklist.

The studies found significant differences in these areas in the brains of psychopaths:

  1. Amygdala
  2. Prefrontal cortex
  3. Paralimbic structures
  4. Ventral striatum

So why are these particular areas important when it comes to psychopathic behaviour?

The Function of the Amygdala

The amygdala is our emotional centre. It is responsible for the perception of our primary emotions such as fear, anger, sadness, love, as well as controlling our impulses and aggression.

The amygdala is also a key part of our learning processes. It teaches us about the society we live in; in other words, acceptable rules and boundaries. Furthermore, it reinforces what is dangerous and helps us to recognise threats and danger.

In the study, psychopaths were shown a series of disturbing images. Some were fearful faces, others depicted moral violations. In a psychopath’s brain, activity in the amygdala was significantly reduced when they viewed the disturbing images.

This means that a psychopath has not learned to live within societal rules. They don’t recognise normal etiquette or boundaries. Looking at people who are frightened doesn’t bother them.

Reduced activity in the amygdala also has the effect of dampening down fear responses. Moreover, our emotional reaction to fear in other people is also reduced. The study showed that the higher the participants scored on the Hare Checklist, the lower the activity in the amygdala.

The Function of the Prefrontal Cortex

The prefrontal cortex is our personality centre. It controls impulses, planning, the choices you make, self-control, short-term and long-term decision-making. This area is responsible for all the higher-level functions that make us human and differentiate us from other animals.

To give you an idea of what damage to the prefrontal cortex can do, one famous case is Phineas Gage. Gage suffered a devastating injury from a tamping iron to his brain into the prefrontal cortex area. His personality changed drastically overnight. Before the accident, Gage was a mild-mannered, hardworking and loving husband. Afterwards, he became violent, aggressive, ill-mannered and abusive.

The study showed that psychopaths have much less grey matter in a section of the prefrontal cortex called the orbitofrontal cortex (OFC). The OFC is thought to be involved with impulse control and decision-making. It is also important in reward-association.

The prefrontal cortex monitors our behaviour. They are our brakes, they control our impulses and stop us doing whatever we want.

Normal people might think ‘I want to kill my boss, he is so stupid,’ but we would never dream of acting on our thoughts because we know it is wrong, there are consequences to our actions. Imagine having no control or brakes on our thoughts. Any reduction in this area would lead a person to act without consequences.

Conversely, this area activates and light up when a psychopath watches someone being hurt or punished.

The Function of the Paralimbic Structures

The paralimbic structures are responsible for recall and memory. They control our short-term memory and episodic memory. But what does this mean in real life? I always give this as an example to describe episodic memory – my episodic memory is recalling a sports day at school when I won second prize for the 400m.

The limbic system is also closely tied into the amygdala which regulates emotions, and emotions are closely tied in with memories. So what does this have to do with psychopaths?

The brains of psychopaths show a significant reduction in volume in the paralimbic system. A decrease in this area is linked to impairments in recalling episodic memories.

But why is this important? If you can’t remember what has happened in your own past, you might recall it differently to how it actually occurred. You may see your part in the experience as a more important role and others as having weaker ones.

The Function of the Ventral Striatum

The ventral striatum is responsible for our reward and motivation processing. This area controls anticipation, decision-making and reward outcomes. This area is associated with instant gratification or immediate gain.

In the study, the inmates with the greatest activity in the ventral striatum also scored highly for psychopathy. This indicates that they are over-valuing the immediate reward and are not able to wait for a later one.

Not only that but the study found a weakened connection between the ventral striatum and an area in the prefrontal cortex. This area is responsible for our ability to mentally ‘time leap’ and look into the future. People with normal brains can envisage the consequences of our actions. Psychopaths can’t do this.

“We need the prefrontal cortex to make prospective judgements how an action will affect us in the future — ‘If I do this, then this bad thing will happen.’ The way we think of it is if you break that connection in anyone, they’re going to start making bad choices because they won’t have the information that would otherwise guide their decision-making to more adaptive ends.” Buckholtz

All this research throws up some interesting questions.

If a psychopath’s brain is different, shouldn’t they be treated differently? If a person suffered a brain injury then went on to commit a crime, we would not send them to prison. So why do we continue to incarcerate psychopaths when we know their brains do not function the same way normal ones do?

Buckholtz wants society to see psychopaths the same way we see other people with poor impulse control and decision-making. He wants us to see them as people with brain deficits that need our help. Unfortunately, it might be a long time before we are able to do that.


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