The connection between serious brain injuries and antisocial personality disorder is not fully understood. However, traumatic brain injury (TBI) has been found to correlate with antisocial behavior in some studies. Several notable serial killers—many of whom could qualify for a diagnosis of antisocial personality disorder—had significant head injuries in their youth, suggesting there may be a direct causal link between early brain damage and later violent behavior. However, such a link is still speculative; because such injuries typically occurred early in childhood, it’s difficult to determine if they directly caused later antisocial behavior—or, if they did play a role, whether they were more or less influential than other genetic or environmental factors.
Traumatic brain injury that occurs in adulthood can also trigger mood and personality changes, including, in some cases, anger or aggression. However, an adult acting violently or antisocially after a brain injury would not qualify for a diagnosis of antisocial personality disorder, as ASPD, by definition, is a deeply-rooted and enduring pattern of behavior that is present from childhood onward.