Excerpted From: Shelby Hunter, Lauren E. Kois, Ashley T. Peck, Eric B. Elbogen and Casey LaDuke, The Prevalence of Traumatic Brain Injury (TBI) among People Impacted by the Criminal Legal System: An Updated Meta-analysis and Subgroup Analyses, 47 Law and Human Behavior 539 (October, 2023) (6 Footnotes/References) (Full Document)


TBI CriminalObjective: Traumatic brain injury (TBI) is a significant public health concern and has implications for people directly impacted by the criminal legal system during arrest, conviction, incarceration, and community supervision. This meta-analysis estimated the lifetime prevalence of TBI among people supervised by the criminal legal system across settings. Hypotheses: Building on previous research, we hypothesized that prevalence estimates would be impacted by methodological, clinical, and demographic factors. Method: Eligible studies included those with adult participants supervised by the criminal legal system (i.e., prison, jail, probation, parole, inpatient/forensic hospital) and that provided sample TBI prevalence and method of ascertaining TBI history. We employed subgroup analyses and metaregression to investigate the effects of setting, TBI definition and method of detection, lifetime history of mental illness and substance use disorders, and gender. Results: The sample ultimately included 64 studies totaling 52,540 participants. Using a random-effects model and logit transformation, we found that the overall estimate of TBI prevalence was 45.8% (95% confidence interval, 95% prediction interval,  across all studies and 32.0%, 95% PI for moderate-to-severe TBI. Significant effects were found for TBI definition and method of detection on the pooled estimate. Conclusions: The prevalence of TBI among people impacted by the criminal legal system may be larger than in the general population. However, despite recent and ongoing progress in this area of study, the reliability of prevalence estimates remains limited by methodological factors related to TBI definitions and detection methods. Implications for TBI research and clinical service provision are discussed.

Public Significance Statement

This study estimated high rates of lifetime traumatic brain injury (TBI) history among people impacted by the criminal legal system. We also found that TBI rates significantly differ depending on how researchers define and measure TBI. These findings emphasize the importance of standardized TBI research methods and support the need for increased TBI screening procedures for individuals in criminal legal settings.

Keywords: traumatic brain injury, head injury, corrections, criminal legal system, incarceration

Traumatic brain injury (TBI) is a significant public health concern, with approximately 69 million cases globally and 1.7 million cases in the United States each year. The Centers for Disease Control and Prevention (CDC) estimated that there were approximately 224,000 TBI-related hospitalizations and 61,000 TBI-related deaths in the United States in 2017. TBI is also a major cause of long-term disability for an estimated 3.32 million people in the United States. Estimates of TBI lifetime prevalence in the general adult population have ranged from 12% to 24%.

For people impacted by the criminal legal system, these rates are significantly higher. The prevalence of TBI among legally impacted individuals (i.e., ~1.8 million people incarcerated and 3.7 million under community supervision in 2021;  has been estimated at 51%-60%. TBI and rule-violating behavior have a complex relationship, with implications for individuals who have acquired TBI, those who may provide psychological services for individuals with a history of system involvement, and the public at large.

The TBI-offending connection is well established and complex. For instance, although numerous studies have identified TBI as a significant risk factor for offending and aggression, they point to a nuanced--rather than causal--relationship. For instance, some longitudinal research has found that post-TBI offending was related to premorbid factors that increase offending risk in general, such as arrest history, male sex, age, and substance misuse. Other longitudinal research found significantly increased risk of incarceration and convictions for violent crime even after adjusting for biological, behavioral health, and structural factors. However, such increased risk has not been supported in all longitudinal studies  or for all hypothesized outcomes (e.g., violent but not general offenses. The TBI-offending relationship has also been linked to postinjury psychosocial factors, including stress, depression, and impaired social functioning.

In sum, although the relationship between TBI and offending remains complex, TBI history has been consistently associated with psychosocial and cognitive difficulties for individuals navigating the criminal legal system. For instance, among incarcerated populations, TBI has been associated with mood dysregulation, mental health diagnoses, substance use, and cognitive complaints. Among individuals under community supervision, TBI has been associated with lower rates of successful probation completion and higher rates of reoffending. Understanding how to mitigate these factors is paramount.

Encouragingly, some small-scale interventions have shown success for individuals with TBI. However, at the public health level, a clear first step is understanding the scope of the problem to determine the need and resources necessary for intervention. Although the previous systematic reviews and meta-analyses provided TBI prevalence estimates among some system-impacted populations, none encompassed the entirety of criminal legal system settings. TBI is not typically assessed with regularity or consistency in criminal legal settings, and detection methods may significantly impact these estimates. Reviews that weigh these critical considerations will provide much-needed detail on TBI prevalence among individuals in criminal legal settings. Further, doing so will inform the extent to which health services resources such as TBI-relevant interventions should be accessible to these populations.

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The results of this meta-analysis indicate that nearly half of all individuals impacted by the criminal legal system have sustained some form of TBI at some point in their lifetime, and nearly a third have sustained a serious TBI. This has important implications for behavioral, cognitive, and emotional functioning during both incarceration and community reintegration. These findings also revealed important differences in prevalence estimates based on TBI research methodology, highlighting the need for standardized TBI assessment practices in these settings. Given the existing health disparities among this population, future efforts should be directed toward improving TBI identification and service provision to improve quality of life and postrelease functioning and ultimately to reduce recidivism among individuals impacted by our criminal legal system.

Bradley D. McAuliff served as Action Editor.
Shelby Hunter (iD) https://orcid.org/0000-0001-7676-1832
Lauren E. Kois (iD) https://orcid.org/0000-0001-6926-7588
Casey LaDuke (iD) https://orcid.org/0000-0002-5415-713X