According to researchers, people who steal, lie and bully others throughout their lives may have smaller brains than normal people.
Brain scans of some 45-year-olds who had antisocial behavior from childhood showed they had smaller brains than normal people, but they point out that it remains unclear whether the brains of the people who took part in the study were inherited, or had undergone these changes due to substance abuse or poor mental health.
Researchers scanned the brains of 700 participants who engaged in antisocial behavior; people who had violent behavior, had committed crimes, or had mental problems due to narcotic substances.
The authors said the findings, published in the Lancet Psychiatry journal, provided the first strong evidence to show that people who had bad behavior in their lifetime had major neuropsychological problems.
Lead study author Christina Carlisi, from the University of London, said differences in their brain structure make it harder to develop the social skills that prevent them from engaging in anti-social behaviour.
Meanwhile, Graeme Fairchild, another author of the study, said that the research was an important contribution, but added that this study should be continued to more clearly determine other details of the mental health of these people.