A new study has shown that people with psychopaths have a larger area of striatum in their brains
Neuroscientists using MRIs have found that psychopathic people have a 10% larger striatum, a group of neurons in the subcortical basal ganglia of the forebrain, than ordinary people. This represents a clear biological distinction between psychopaths and non-psychopathic people.
Neuroscientists from Nanyang Technological University (NTU Singapore), University of Pennsylvania and California State University have discovered a biological distinction between psychopaths and non-psychopaths. Using magnetic resonance imaging (MRI), scientists found that the striatum, an area of the forebrain, was 10% larger in psychopathic people compared to a control group of individuals with little or no psychopathic traits.
Psychopaths, or those with psychopathic qualities, are people who have a selfish and antisocial disposition. This is often characterized by a lack of guilt for their actions, a lack of empathy for others, and in some cases, criminal tendencies.
The striatum, which is part of the forebrain, the subcortical region of the brain that encompasses the entire brain, coordinates many elements of cognition, including motor and action planning, decision making, motivation, reinforcement and the perception of rewards.
Previous research has shown that psychopaths have an overactive striatum, but the influence of its size on behavior has yet to be confirmed. The new research demonstrates a significant biological difference between people who exhibit psychopathic tendencies and those who do not. Although not all people with psychopathic qualities end up breaking the law, and not all criminals meet the criteria for psychopathy, there is a strong association. There is also significant evidence that psychopathy is associated with more aggressive 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, of NTU’s School of Social Sciences, neurocriminologist co-author of the study, said: “The results of our study help advance our knowledge of what underlies antisocial behaviors such than psychopathy. We find that in addition to social environmental influences, it 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.
Professor Adrian Raine from the Departments of Criminology, Psychiatry and Psychology at the University of Pennsylvania, co-author of the study, said: “Because biological traits, such as the size of one’s striatum, can be inherited from parent to child, these findings provide further support for neurodevelopmental perspectives of psychopathy – that the brains of these offenders do not develop normally throughout childhood and adolescence.
Professor Robert Schug of the School of Criminology, Criminal Justice and Emergency Management at California State University, Long Beach, co-author of the study, added: “Using the list The Revised Psychopathy Control in a Community Sample remains a new scientific approach: Helping us understand psychopathic traits in individuals who are not in jails and jails, but rather in those who walk among us every day.
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 Psychiatric Research Journal.
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 discerns what sensory information deserves 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 examined 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 suggested “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 related to a structural abnormality of the brain which may be developmental in nature. At the same time, it is important to recognize that the environment can 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 discovering a neurobiological basis for this impulsive and challenging behavior in the form of an enlargement of 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.
Reference: “Greater striatal volume is associated with increased adult psychopathy” by Olivia Choy, Adrian Raine and Robert Schug, March 6, 2022, Psychiatric Research Journal.