The approach to quantifying a possible connection between brain injury and criminal behavior—and using that data to aide in inmate rehabilitation—arose three years ago. Over a two-year period, Gorgens graduate students assessed 80 inmates in the Van Cise-Simonet Detention Center in Denver, which houses arrestees as they await sentencing. The findings from the pilot study were staggering: Ninety-six percent of inmates screened had suffered moderate or severe brain trauma. It was a sharp contrast to the estimated 6 percent of the general population with similar brain injuries, but it did match up with previous, similar studies from the past two decades. A 2008 study of 990 Minnesota inmates found a rate of 80 percent; a 2006 analysis of 200 Australian prisoners found 82 percent; and a 2007 survey of 107 male and 118 female inmates from six federal prisons found 87 percent.
Head injuries early in life can lead to aggressive behavior later on. An eight-year study that followed ninth-graders in Flint, Michigan, into adulthood found that young people who had endured head injuries were more likely to engage in violent acts later—fighting, hurting someone badly enough that they required medical attention or threatening someone with a knife, gun or club—than those who had not. Adults with a history of traumatic brain injuries also tend to enter prison at a younger age, according to an analysis in Brain Injury. A 2009 study of head trauma patients in Maryland found that within three months after a head injury, 28 percent of patients became aggressive.