Psychopathic individuals have a 10% larger striatum in the brain compared to others, study finds

Neuroscientists from Nanyang Technological University in Singapore (NTU Singapore), the University of Pennsylvania and California State University have established the existence of a biological difference between psychopaths and non-psychopaths .

Using magnetic resonance imaging (MRI), they found that a region of the forebrain known as the striatum was on average ten percent larger in psychopathic individuals compared to a control group. individuals with few or no psychopathic traits.

Psychopaths, or those with psychopathic traits, are generally defined as individuals who have self-centered and antisocial personalities. This is normally marked by a lack of remorse for their actions, a lack of empathy for others, and often criminal tendencies.

The striatum, which is part of the forebrain, the subcortical region of the brain that contains the entire brain, coordinates multiple aspects of cognition, including motor and action planning, decision making, motivation, reinforcement and the perception of rewards.

Previous studies have found evidence of an overactive striatum in psychopaths, but have not conclusively determined the impact of its size on behaviors. The new study reveals a significant biological difference between people who have psychopathic traits and those who don’t.

Although not all individuals with psychopathic traits end up breaking the law, and not all criminals meet the criteria for psychopathy, there is a marked correlation. There is clear evidence that psychopathy is linked to more violent behavior.

Understanding the role of biology in antisocial and criminal behavior can help improve existing theories of behavior, as well as inform policy and treatment options.

To conduct their study, the neuroscientists scanned the brains of 120 participants in the United States and interviewed them using the Psychopathy Checklist – Revised, a psychological assessment tool to determine the presence of psychopathic traits in individuals.

Assistant Professor Olivia Choy, from NTU’s School of Social Sciences, a neurocriminologist who co-authored the study, said: “The results of our study help advance our knowledge of what underlies antisocial behavior such as psychopathy. We find that in addition to social environmental influences, there is important to consider that there may be differences in biology, in this case the size of brain structures, between antisocial and non-antisocial individuals.”

Given that biological traits, such as the size of one’s striatum, can be inherited from the child’s parents, these findings provide further support for neurodevelopmental perspectives of psychopathy – that the brains of these offenders do not develop normally. throughout childhood and adolescence..”

Adrian Raine, Study Co-Author and Professor, Departments of Criminology, Psychiatryand Psychology, University of Pennsylvania

Professor Robert Schug of the School of Criminology, Criminal Justice and Emergency Management at California State University, Long Beach, who co-authored the study, said: “Using the Psychopathy Checklist – Revised in a Community Sample remains a new scientific approach: to help us understand psychopathic traits in individuals who are not in prison and in prison, but rather among those who walk among us daily.”

Highlighting the importance of the work done by the joint research team, Associate Professor Andrea Glenn of the Department of Psychology at the University of Alabama, who is not involved in the research, said: “By reproducing and By extending previous work, this study increases our confidence that psychopathy is associated with structural differences in the striatum, a brain region that is important in a variety of processes important to cognitive and social functioning. Future studies will be needed to understand the factors that may contribute to these structural differences.

The results of the study were published recently in the peer-reviewed academic publication JJournal of Psychiatric Research.

Bigger striatum, bigger appetite for stimulation

Using MRI scans and interview results to screen for psychopathy, researchers have linked having a larger striatum to an increased need for stimulation, through thrills and arousal, and a higher likelihood of impulsive behaviors.

The striatum is part of the basal ganglia, which are made up of clusters of neurons located deep in the center of the brain. The basal ganglia receive signals from the cerebral cortex, which controls cognition, social behavior, and the discernment of sensory information worthy of our attention.

Over the past two decades, however, understanding of the striatum has expanded, suggesting that the area is linked to difficulties in social behavior.

Previous studies have not examined whether striatal enlargement is seen in adult women with psychopathic traits.

The neuroscientists say that in their study of 120 people, they looked at 12 women and observed, for the first time, that psychopathy was linked to an enlarged striatum in women, just like in men. In human development, the striatum typically becomes smaller as the child grows, suggesting that psychopathy may be linked to differences in brain development.

Assistant Professor Choy added: “A better understanding of the development of the striatum is still needed. Many factors are likely involved in why one individual is more likely to have psychopathic traits than another individual. Psychopathy may be linked to a structural abnormality of the brain that may be developmental in nature.At the same time, it is important to recognize that the environment may also have effects on the structure of the striatum.

Professor Raine added: “We have always known that psychopaths go to great lengths to seek rewards, including criminal activity involving property, sex and drugs. We are now uncovering a neurobiological basis for this impulsive and stimulating behavior under the form of an enlargement in the striatum, a key brain area involved in rewards.

Scientists hope to conduct further research to uncover the causes of striatum enlargement in individuals with psychopathic traits.


Journal reference:

Choy, O. et al. (2022) Larger striatal volume is associated with increased adult psychopathy. Psychiatric Research Journal.

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