Persistent antisocial behavior linked to smaller brain size

By Angela Betsaida B. Laguipo, BSNFeb 18 2020

Antisocial behavior is characterized by disruptive acts of intentional aggression that causes distress, alarm, or harassment toward others. People who exhibit antisocial behavior since they were children through adulthood are more likely to have smaller brains, a new study found.

A team of researchers at the University College of London (UCL) has found that adults with a long history of offenses show marked differences in brain structure than those who have behaved well or those who transgressed only in adolescence.

The study, which was published in the journal The Lancet Psychiatry, showed that MRI brain scans of those who exhibit life-course-persistent antisocial behavior including aggression, stealing, violence, lying, bullying and repeated failure to take care of school and work responsibilities had thinner cortex and smaller surface area in parts of the brain linked to antisocial behavior, compared to those without the behavior.

The researchers used structural MRI data collected at 45 years of age from participants in the Dunedin Study, a population-representative longitudinal birth cohort of 1,037 individuals born between April 1, 1972, and March 31, 1973, in Dunedin, New Zealand. Image Credit: Gorodenkoff / Shutterstock

Changes in brain structure

To arrive at their findings, the researchers recruited 672 adults who underwent MRI scans at the age of 45. Aside from brain scans, the team also gathered histories of the patients, particularly their behaviors. They compared the brain compositions of those with a history of antisocial behavior to those without.

The team divided the participants depending on the behavior they exhibited – 12 percent had life-course-persistent antisocial behavior, 23 percent had adolescent-only antisocial behavior, and 66 percent had no history of antisocial behavior.

They studied the brain scans of the participants, measuring and comparing the average thickness and surface area of the cortices.

The team also found that the marked changes in brain structure were only seen in those who exhibited antisocial behavior throughout their lifetime, not in those who had antisocial behavior only during their teenage years. The people who had life-course-persistent antisocial behavior had reduced surface area in 282 of 360 brain regions and had thinner cortex in 11 of 360 regions.

More attention to toddlers and children

The researchers also said that it's essential to pay more attention to toddlers and children who exhibit antisocial behaviors, those who persistently badly-behaved since they're at a higher risk of living a life with antisocial behavior because of the way their brains formed.

Further, the team also said that teens who exhibit antisocial behavior since they were kids are often diagnosed with conduct disorder. They are at a greater risk of imprisonment, poor physical health, and poor mental health later in life.

"Our findings support the idea that, for the small proportion of individuals with life-course-persistent antisocial behavior, there may be differences in their brain structure that make it difficult for them to develop social skills that prevent them from engaging in antisocial behavior. These people could benefit from more support throughout their lives," Dr. Christina Carlisi from the University College London and lead author of the study, said.

"Most people who exhibit antisocial behavior primarily do so only in adolescence, likely as a result of navigating socially difficult years, and these individuals do not display structural brain differences. It is also these individuals who are generally capable of reform and go on to become valuable members of society," Dr. Carlisi added.

The team believes that the study highlights the need for different approaches for various offenders. However, they also admitted the limitations of the study, as the brain imaging and understanding brain structures are not strong enough to be applied on the individual level.

"It is unclear whether these brain differences are inherited and precede antisocial behavior, or whether they are the result of a lifetime of confounding risk factors (e.g., substance abuse, low IQ, and mental health problems) and are therefore a consequence of a persistently antisocial lifestyle," Professor Essi Viding of UCL, added.

The team encourages others to conduct further research, including in the measurements of the genes, behavior, and environment to land to more robust findings.