Despite current public and expert opinion to the contrary, having the neurological condition epilepsy is not directly associated with an increased risk of committing violent crime. However, there is an increased risk of individuals who have experienced previous traumatic brain injury going on to commit violent crime according to a large Swedish study led by Seena Fazel from the University of Oxford, UK, and colleagues at the Karolinska Institutet, Sweden, and Swedish Prison and Probation Service, and published in this week's PLoS Medicine.
The authors say: "The implications of these findings will vary for clinical services, the criminal justice system, and patient charities."
In their study, the authors identified all people with epilepsy and traumatic brain injury recorded in Sweden between 1973 and 2009 and matched each case with ten people without these brain conditions from the general population. The investigators linked these records to subsequent data on all convictions for violent crime using the personal identification numbers that identify Swedish residents in national registries.
Sweden's extensive record keeping on its populace sure comes in handy for scientific research.
I don't think these results mean what these researchers think they mean. Just because other non-epileptic family members of epileptics have the same increased risk of violent crime does not mean that epileptics aren't at increased risk of committing violent crime.
Using these methods, the authors found that 4.2% of people with epilepsy had at least one conviction for violence after their diagnosis compared to 2.5% of the general population. However, after controlling for the family situation (in which individuals with epilepsy were compared with their unaffected siblings), the association between being diagnosed with epilepsy and being convicted for violent crime disappeared.
A plausible explanation: genetic variants that increase the risk of developing epilepsy also boost the risk of crime regardless of whether they cause epilepsy in their carriers. Though even if some genetic variants contribute to epilepsy risk and violence that does not mean that all genetic variants that contribute to one also contribute to the other. Also, even if some genetic variant contributes to both epilepsy and violence that does not mean that variant increases the risk of violent crime in all carriers. Other genetic variants elsewhere in the genome could cancel out violent crime risks in some carriers. The interactions between human brain genes are going to be enormously difficult to discover and model.
Traumatic brain injury is linked to higher risk of committing violent crime. There ar4e plausible mechanisms of causation in both directions. Obviously brain damage could harm brain circuitry that restrains behavior or it could enhance anger that people feel when insulted or could work via some other mechanism to make violent acts more likely. Though people who are violent in the first place are at greater risk of getting their brains beaten on in a fight or damaged in a road rage incident. The full research paper (linked in the first paragraph) even mentions that brain trauma is common in prison.
In contrast, the authors found that after controlling for substance abuse or comparing individuals with brain injury to their unaffected siblings, there remained an association between experiencing a traumatic brain injury and committing a violent crime.
Given the high incidence of traumatic brain injury from improvised explosive devices (IEDs) among US military veterans that served in Iraq and Afghanistan some of these veterans might be at greater risk of violence as a result.
The full paper even mentions that some subtypes of epilepsy are associated with a reduced risk of violent crime.
|Share |||Randall Parker, 2012 January 01 11:04 PM Brain Violence|