Historically, there has been an association of violent crime and traumatic
brain injury (TBI). There are numerous case studies of violent behaviors
after TBI, and there is an extremely high prevalence of prisoners with
TBI. This association is in part due to the vulnerability of the frontal
lobe to injury-the frontal lobe is critical for emotional control and
inhibition of inappropriate responses and behaviors (among other things).
However, there is little research that supports the causal relationship
of TBI and violent crime. Other factors such as substance abuse, impulsivity
as an inherited trait, and socio-economic status can also contribute to
Researchers recently found that, after controlling for these confounding
factors, there was still a direct association between violent crime and
TBI. In addition, injuries to the frontal lobe were significantly more
likely to be associated with violent crime than other areas of injury.
Despite the fact that substance abuse and impulsivity can increase the
risk of TBI, the study found that a frontal lobe injury can independently
increase violent behavior.
Faxel S, Lichtenstein P, Grann M, & Langstrom Niklas. Risk of violent
crime in individuals with epilepsy and traumatic brain injury: A 35-year
Swedish population study. PLOS Medicine. (December 2011).