From: Yanyang Technological University
Singapore, 10 May 2022 –
A study finds psychopathic individuals are more likely to have larger striatum
region in the brain
Neuroscientists from
Nanyang Technological University, Singapore (NTU Singapore), 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) scans, they found that a region of the forebrain known
as the striatum, was on average ten per cent larger in psychopathic individuals
compared to a control group of individuals that had low or no psychopathic
traits.
Psychopaths, or those
with psychopathic traits, are generally defined as individuals that have an
egocentric and antisocial personality. 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
a part of the forebrain, the subcortical region of the brain that contains the
entire cerebrum, coordinates multiple aspects of cognition, including both
motor and action planning, decision-making, motivation, reinforcement, and
reward perception.
Previous studies have
pointed to an overly active striatum in psychopaths but have not conclusively
determined the impact of its size on behaviours. The new study reveals a
significant biological difference between people who have psychopathic traits
and those who do not.
While 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 behaviour.
The understanding of
the role of biology in antisocial and criminal behaviour may help improve
existing theories of behaviour, as well as inform policy and treatment options.
2
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: “Our study’s results help advance our knowledge
about what underlies antisocial behaviour such as psychopathy. We find that in
addition to social environmental influences, it is important to consider that
there can 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 University
of Pennsylvania, who co-authored the study, 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.”
Professor Robert Schug
from the School of Criminology, Criminal Justice, and Emergency Management at
California State University, Long Beach, who co[1]authored the study,
said: “The use of the Psychopathy Checklist - Revised in a community sample
remains a novel scientific approach: Helping us understand psychopathic traits
in individuals who are not in jails and prisons, but rather in those who walk
among us each day.”
Highlighting the
significance of the work done by the joint research team, Associate Professor
Andrea Glenn from the Department of Psychology of The University of Alabama,
who is not involved in the research, said: “By replicating and extending prior
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 for 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 Journal
of Psychiatric Research.
Bigger striatum, larger
appetite for stimulation
Through analyses of the
MRI scans and results from the interviews to screen for psychopathy, the
researchers linked having a larger striatum to an increased need for
stimulation, through thrills and excitement, and a higher likelihood of
impulsive behaviours. 3
The striatum is part of
the basal ganglia, which is made up of clusters of neurons deep in the centre
of the brain. The basal ganglia receive signals from the cerebral cortex, which
controls cognition, social behaviour, and discerning which sensory information
warrants attention.
In the past two
decades, however, the understanding of the striatum has expanded, yielding
hints that the region is linked to difficulties in social behaviour.
Previous studies have
not addressed whether striatal enlargement is observed in adult females with
psychopathic traits.
The neuroscientists say
that within their study of 120 individuals, they examined 12 females and
observed, for the first time, that psychopathy was linked to an enlarged
striatum in females, just as in males. In human development, the striatum
typically becomes smaller as a child matures, suggesting that psychopathy could
be related to differences in how the brain develops.
Asst Prof Choy added:
“A better understanding of the striatum’s development is still needed. Many
factors are likely 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.”
Prof Raine added: “We
have always known that psychopaths go to extreme lengths to seek out rewards,
including criminal activities that involve property, sex, and drugs. We are now
finding out a neurobiological underpinning of this impulsive and stimulating
behaviour in the form of enlargement to the striatum, a key brain area involved
in rewards.
The scientists hope to
carry out further research to find out the causes of the enlargement of the
striatum in individuals with psychopathic traits.
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