According to a large Swedish investigation published in PloS Medicine, epilepsy is not directly linked to an increased risk of committing violent crime. Although, individuals who previously experienced traumatic brain injury (TBI) have an increased risk of committing violent crime. The investigation was led by Seena Fazel, from the University of Oxford, UK, and colleagues at the Karolinska Institutet, Sweden, and Swedish Prison and Probation Service.
The researchers explain:
“The implications of these findings will vary for clinical services, the criminal justice system, and patient charities.”
The team identified all individuals in Sweden recorded with TBI and epilepsy between 1973 and 2009. They then matched 10 individuals without these conditions from the general population to each case. These records were then linked to later data on all violent crime convictions using personal identification numbers that identify individuals in Sweden in national registries.
They discovered that 4.2% of individuals with epilepsy had committed at least one violent crime after diagnosis in comparison with 2.5% of those without these brain conditions. However, the connection between epilepsy and committing violent crime vanished after the team adjusted for the family situation (in which those with the condition were compared with their unaffected siblings). However, after adjusting for substance abuse or comparing those with epilepsy to their unaffected siblings, the team discovered a connection remained between TBI and committing violent crime.
The researchers explain:
“With over 22,000 individuals each for the epilepsy and traumatic brain injury groups, the sample was, to our knowledge, more than 50 times larger than those used in previous related studies on epilepsy, and more than seven times larger than previous studies on brain injury.
In conclusion, by using Swedish population-based registers over 35 years, we reported risks for violent crime in individuals with epilepsy and traumatic brain injury that contrasted with each other, and appeared to differ within each diagnosis by subtype, severity, and age at diagnosis.”
According to the researchers, the lack of a causal connection between violent crime and epilepsy might be helpful for patient charities as well as other stakeholders in fighting one of the causes of stigma linked to epilepsy. Enhanced screening and management of some individuals and prisoners with TBI might lower offense rates.
The investigation relied on conviction data and the researchers explain their hypothesis:
“Although we relied on conviction data, other work has shown that the degree of underestimation of violence is similar in psychiatric patients and controls compared with self-report measures, and hence the risk estimates were unlikely to be affected…We have no reason to this that this would be different for those two neurological conditions. Overall rates of violent crime and their resolution are mostly similar across western Europe, suggesting some generalizability of our findings.”
In an associated Perspective, psychiatrist Jan Volavka, professor emeritus from the New York University School of Medicine (uninvolved in the investigation) explains:
“Comparing the conviction rates before and after the diagnosis would provide another perspective on the effect of the illness on violent crime. Among the major strengths of the study are the very large sample size, comprising the entire population of Sweden, and the follow-up of 35 years. The findings are of major public health importance and provide inspiration for further research.”
Written by Grace Rattue