A recent study found that 96% of inmates in a high risk unit of the Denver jail have a history of traumatic brain injury. By comparison, 67%-80% of all jail and prison inmates, nationally, have a history of traumatic brain injury, and 6%-8.5% of the general population has suffered from a traumatic brain injury. While an above average rate of traumatic brain injury had been expected, the near universal history of traumatic brain injury among high risk inmates was not.
In the Denver high risk jail unit, 100% had a prior criminal history, more than 90% had a history of mental illness and more than 90% had a history of substance abuse. More than 77% of the inmates in the high risk unit had all four risk factors.
A comprehensive metaanalysis of TBI incidence from 2003 can be found here. This points to an important indirect source of the large male-female disparity in serious crime rates. "The high M/F ratio is mainly the result of interpersonal violence and motor vehicle collisions during adolescence and young adulthood. During these “testosterone years,” the M/F ratio can approach or exceed 3 to 4:1." This disparity in TBI incidence, in turn leads to a disparity in serious crime incidence in which TBI is a contributing factor (where the disparity is even more extreme).
A study reviewing TBI incidence in Australian prisons from 2006 found an 82% TBI incidence rate. Another county jail study from 2003 found an 87% lifetime incidence of TBI. A 1995 study examined the way the substance abuse can exacerbate TBI issues.
Generally speaking, TBI cannot be "cured" although it is possible to teach people with TBI how to better deal with the symptoms and to provide more support for them.
UPDATE: March 22, 2015
Note directly related, but relevant is the data on PTSD on soldiers who have served in combat. The recent U.S. wars have sent many soldiers who served in combat home with PTSD and has sent many home with TBI. Both are invisible. But, we've known about the risks associated with PTSD under different names since WWI at least (and probably sooner), and the risks associated with TBI since the case of Phineas Gage who died in 1860. Our understanding of these conditions is more scientific and precise than it once was, but is hardly new.