Psychopathic tendencies related to size of specific brain region
A region of the brain known as the striatum was found to be on average 10% larger in psychopathic individuals compared to those that had low or no psychopathic traits, according to research led by neuroscientists from Nanyang Technological University (NTU), Singapore. The striatum, part of the deeper structures in the brain, coordinates multiple aspects of cognition such as action planning, decision-making, motivation, reinforcement, and reward perception – the region is also linked to difficulties in social behaviour.
Psychopaths, or those with psychopathic traits, are generally defined as individuals that have an egocentric and antisocial personality as well as a lack of remorse and empathy. People who exhibit psychopathic traits often seek out thrilling activities that are violent and criminal in nature.
Despite a marked correlation, not all individuals with psychopathic traits end up breaking the law, and not all criminals meet the criteria for psychopathy.
Using magnetic resonance imaging (MRI) scans, NTU researchers have identified a significant biological difference between psychopaths and non-psychopaths, relating to the size of the striatum: having a larger striatum is linked to an increased need for stimulation, through thrills and excitement, and a higher likelihood of impulsive behaviours.
In their study, the neuroscientists scanned the brains of 120 participants in the US and interviewed them using the Psychopathy Checklist—Revised, a psychological assessment tool to determine the presence of psychopathic traits in individuals. While previous studies have not addressed whether striatal enlargement is observed in adult females with psychopathic traits, the neuroscientists observed, for the first time, that psychopathy was linked to an enlarged striatum in females, just as in males.
Explaining on the incidence of an enlarged striatum, partner researcher Professor Adrian Raine from the Departments of Criminology, Psychiatry, and Psychology at University of Pennsylvania, US, said: “Because biological traits, such as the size of one’s striatum, can be inherited to child from parent, these findings give added support to neurodevelopmental perspectives of psychopathy—that the brains of these offenders do not develop normally throughout childhood and adolescence.”
In human development, the striatum typically becomes smaller as a child matures, suggesting that psychopathy could depend on differences in how the brain develops.
Neurocriminologist Olivia Choy, an Assistant Professor from NTU’s School of Social Sciences, added: “A better understanding of the striatum’s development is still needed. Many factors are involved in why one individual is more likely to have psychopathic traits than another individual. Psychopathy can be linked to a structural abnormality in the brain that may be developmental in nature. At the same time, it is important to acknowledge that the environment can also have effects on the structure of the striatum.”
The neuroscientists hope to carry out further research to find out definitive causes behind the enlargement of the striatum in individuals with psychopathic traits.
