Psychopaths Are More Likely to Have a Larger Striatum

Psychopathy is the result of a complex combination of factors, both environmental and genetic. Now, scientists have discovered a new brain peculiarity. We explain it to you.
Psychopaths Are More Likely to Have a Larger Striatum

Last update: 06 July, 2022

Recent research has revealed that psychopaths have one part of the brain that’s larger than normal. It’s the striatum, a set of subcortical structures that are part of the basal ganglia. The area is related to important procedural and also emotional processes.

It should be noted, however, that this isn’t the first neurological peculiarity that’s been discovered in terms of psychopathic behavior. Experts have spent several years uncovering, layer by layer, the mystery of this ‘dark personality’. For example, it’s now known that psychopaths have severe alterations in processes such as empathy, feelings of guilt, fear, or anxiety.

However, genetic and neurological alterations aren’t enough to explain why a man or woman is a psychopath. Dr. James Fallon is one of the most prestigious neurologists in the world. He discovered that he has the genes and neurological characteristics of a psychopath.

Moreover, in his paternal family, there were up to seven murderers, one of them being the famous Lizzie Borden. However, Dr. Fallon was raised with love, secure attachment, and a wonderfully nurturing family. In fact, the environment is, in many cases, the factor that activates or deactivates the psychopathy gene, the one that many people carry within them.

Alterations in socio-emotional circuitry are a feature in offenders with psychopathic personalities.

brain symbolizing why psychopaths have a larger than normal brain region
A psychopath has a larger striatum.

Psychopaths are more likely to have a larger striatum

Neuroscientists from Nanyang Technological University in Singapore (NTU Singapore), the University of Pennsylvania, and California State University recently conducted an extremely interesting study. They concluded that a psychopath is more likely to have a larger-than-average striatum.

This factor allows a distinction to be made between those who could and couldn’t present this trait. An MRI is enough to find out. It would probably find that a person with psychopathic traits (active or latent) has a striatum that’s ten percent larger than that of those who lack this characteristic.

So what are the characteristics of the people who present this nuance in their brain? Let’s take a look.

An overactive striatum: the mind in search of rewards

The striatum deals with multiple functions that are essential for the human being. Among them are those related to motor learning, movement, and procedural memory. However, it’s also decisive in tasks such as motivated behavior or the ability to select actions based on expected rewards.

One aspect that defines psychopaths is their instrumental behavior. Indeed, they act only for their own interest and to obtain what they want. The striatum controls, through dopamine secretion, the brain’s reward system. The aforementioned study found that this function is highly active in psychopaths.

Therefore, we’re talking about people with low empathy, but who are highly motivated to achieve what they want (whether legal or not). This results in them not being afraid to violate ethical, moral, and legal principles.

Behavior more prone to violence

Psychopaths have a larger than normal striatum. However, they also present striking structural and functional changes in the brain. A study conducted by the University of Turku (Finland) indicates that they show great impulsiveness, a lack of cognitive control, and poor regulation of emotions.

All of this increases the probability that psychopaths are at the greatest risk of becoming involved in violent and criminal actions. It should be noted, however, that not all people with psychopathic traits cross this threshold. Many become those aggressive colleagues or bosses who abuse their authority and are responsible for disastrous results in their own companies.

It’s important to note that only one percent of the population demonstrates high-grade psychopathy capable of leading them to aggressive and illegal acts. People with low-grade psychopathic traits abound to a greater degree. These people are difficult to live with and they deceive and manipulate others to achieve what they want. It’s reprehensible and unethical conduct but not illegal.

Woman yelling on the phone to symbolize that psychopaths have a larger brain region than normal
The vast majority of psychopaths aren’t in prison, but share social spaces with us.

Conclusion

Professor Adrian Raine, from the Department of Criminology, Psychiatry, and Psychology at the University of Pennsylvania (USA) is a co-author of the study we referred to earlier. He claims that the fact that psychopaths have a larger striatum is hereditary and can be inherited by children from their parents.

Does this mean that having a larger striatum would determine our psychopathic behavior? The answer is no. Having certain brain abnormalities associated with psychopathy doesn’t activate this trait in 100 percent of cases, although it’s obviously a risk. However, as we indicated earlier, there are more associated variables apart from genetic or biological ones.

Growing up in a social and family environment that’s safe, emotionally nurturing, and free of traumatic experiences can numb the development of this trait.

Finally, although everything still isn’t known about this altered personality profile, scientists are becoming closer to unraveling its intricate mysteries.

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  • Olivia Choy, Adrian Raine, Robert Schug. Larger striatal volume is associated with increased adult psychopathy. Journal of Psychiatric Research, 2022; 149: 185 DOI: 10.1016/j.jpsychires.2022.03.006
  • Lauri Nummenmaa, Lasse Lukkarinen, Lihua Sun, Vesa Putkinen, Kerttu Seppälä, Tomi Karjalainen, Henry K Karlsson, Matthew Hudson, Niina Venetjoki, Marja Salomaa, Päivi Rautio, Jussi Hirvonen, Hannu Lauerma, Jari Tiihonen. Brain Basis of Psychopathy in Criminal Offenders and General Population. Cerebral Cortex, 2021; DOI: 10.1093/cercor/bhab072