⬇️ Prefer to listen instead? ⬇️
- Over 50% of incarcerated youth say they have had at least one traumatic brain injury (TBI).
- TBIs in teens are strongly linked to more psychopathic traits, especially acting without thinking and antisocial behavior.
- Lower IQ and substance use both help explain the link between TBI and higher criminal behavior.
- Psychopathic traits linked to TBI are mostly about emotions and behavior—not manipulation of others.
- Early help for TBI could mean less involvement with the law and better mental health.
What happens when a teen brain that is still developing is injured? It might be more complicated and have a bigger effect than you think. New research is showing a strong connection between traumatic brain injury (TBI) and more psychopathic traits in young people in jail. As we learn more, it’s clear that understanding this link is key to improving mental health care, guiding changes to the justice system, and directing prevention efforts.
Understanding Traumatic Brain Injury in Youth
A traumatic brain injury (TBI) happens when a sudden force—like a hit, bump, or something piercing the head—changes how the brain works. Even what seem like small injuries can be serious when they happen during childhood or the teen years, a time when the brain is still growing. Common causes of TBI in youth are
- Sports injuries (like concussions in football or soccer)
- Car accidents
- Falls, especially from high places
- Physical abuse and violence at home
- Fights or attacks
Unlike adults, teen brains are still making important connections, especially in the parts that handle thinking, self-control, and feeling for others. TBIs during this important time can throw off normal growth.
Prevalence in Justice-Involved Youth
While TBIs can happen to any young person, they are much more common in young people who are in the justice system. One recent study found that over 50% of young people in jail in a high-security place had experienced at least one TBI (Milillo et al., 2024). This number is much higher than in teens in general, where it’s thought to be between 10% and 20%.
These injuries could be from dangerous environments, not getting the right care, or risky actions—all of which are more common in youth who are not well-off or are at risk.
Long-Term Effects of Adolescent TBIs
The effects of a TBI are not always right away—but they often last a long time. Common problems can be
- Trouble with memory and focus
- Unstable emotions or quick mood changes
- Slower reactions
- Poor judgment and decision-making
- Sleep problems
- Problems with friends and family
These symptoms can lead to doing poorly in school, feeling alone, and more behavior problems—especially if they are not found or treated.
What Are Psychopathic Traits?
“Psychopathy” often makes people think of evil bad guys, but in psychology, it’s a detailed and measurable idea that describes a group of traits across emotions, relationships, behavior, and antisocial actions.
Clinical Breakdown of Psychopathic Traits
Researchers break psychopathy into two main parts, each with several traits
Factor 1: Affective/Interpersonal
- Lack of feeling for others or guilt
- Seeming charming on the surface
- Using people
- Being cold-hearted
- Not showing much emotion
Factor 2: Lifestyle/Antisocial
- Acting without thinking
- Not being responsible
- Lying all the time
- Acting aggressively or violently
- Breaking rules and laws
In teens, these traits might show up as often breaking rules, not having deep feelings for others, and trouble understanding how others feel. It’s important to know that in youth, psychopathy is seen as more able to be changed than in adults—making it very important to help early.
Measuring Psychopathy in Youth
Tools like the Youth Psychopathic Traits Inventory (YPI) and Psychopathy Checklist: Youth Version (PCL:YV) help doctors see how much a young person shows these traits. These tests look at not just actions but also emotional and relationship patterns.
Understanding if and how much psychopathic traits are present in youth helps guide care, plans to help them get better, and even how the law deals with them.
The Adolescent Brain: A Time of Being Easily Harmed
The human brain is not fully grown until the mid-20s, and during the teen years, it’s going through big changes. One of the main changes is the growth of the prefrontal cortex, which is in charge of
- Controlling impulses
- Making decisions
- Managing emotions
- Thinking about what will happen later
This part of the brain is like a “boss”—but it’s one of the last parts to fully grow.
The Unique Risks of TBIs During Adolescence
When a TBI hurts the prefrontal cortex—or messes up the connections between emotional and thinking parts of the brain—the result is often acting without control and changing emotions quickly. Teens with TBIs may
- Take more risks
- Get frustrated more easily
- Have a harder time understanding social cues
- Be more aggressive
This means that a personality that is normally okay can become more antisocial or like psychopathy because of brain injury.
From Trauma to Traits: Key Study Findings
The link between TBI and psychopathy is not just a theory. More and more research is showing a strong connection between brain injury and higher psychopathic traits, especially in young people in the justice system.
Inside the Milillo et al. (2024) Study
In one of the most complete studies so far, researchers looked at 263 teen boys in juvenile detention. Important findings were
- Youth with TBI scored higher on emotional traits (like not feeling for others)
- They also had more unstable lifestyles and antisocial behavior
- It’s worth noting, relationship traits (like charm or manipulation) did not show big differences between those with and without a TBI
These results suggest that TBIs affect emotional control and behavior, not necessarily being socially skilled or good at manipulation. In other words, brain injury may make a young person more impulsive and less emotionally connected, but not necessarily more scheming.
The Mediating Role of Intelligence and Substance Use
Researchers also looked at why TBIs might lead to more psychopathic traits, finding important steps in between: thinking skills going down and more substance use.
Intelligence (IQ) Decline After TBI
TBIs are strongly linked to lower overall IQ, especially in areas like short-term memory, focus, and verbal reasoning. In the study, lower IQ was linked to increases in
- Acting without thinking
- Poor judgment
- Behavior problems starting young
These problems create a base on which antisocial behaviors can grow more easily. A teen who can’t think clearly is more likely to get angry, ignore rules, or do risky things without thinking ahead.
Substance Use as a Coping Strategy
The study also found that youth with several TBIs were more likely to use alcohol and drugs—which, in turn, was related to higher levels of emotional and antisocial traits. This might be because
- They are trying to make themselves feel better from the emotional problems caused by TBI
- They have poor decision-making, leading to trying drugs more
- They are in social groups where youth with TBIs are accepted if they use drugs
So, brain injury → lower IQ + more substance use → more psychopathic behaviors.
TBI and Criminal Behavior: A Dangerous Mix?
When psychopathic traits and TBIs are together, the risk of criminal behavior may be much higher. Factor 2 traits, like acting without thinking and aggression, are directly linked to
- Assault and hitting
- Stealing and robbery
- Damaging property
- Drug crimes
In the justice system, these behaviors often don’t come from being mean, but from a brain that has been neglected or hurt. For example
- A teen with a TBI might think someone is threatening them when they are not, leading to a violent reaction.
- Poor impulse control may make it harder to say no to criminal chances.
- Lack of guilt may come from not feeling emotions strongly, not from being morally bad.
This mix shows that we need thoughtful help, not just punishment.
Causality or Correlation? A Careful Look
The Milillo et al. (2024) study is at one point in time, meaning it shows links but cannot prove cause and effect. There are other possible reasons
- Youth who are likely to be psychopathic may be drawn to risky behaviors that cause TBIs.
- Certain places (like high-crime areas) lead to both trauma and unstable behavior.
However, it makes sense biologically that there is a cause and effect link. We know brain injury disrupts emotional systems, and we know those problems are related to psychopathy scores. The relationship is likely both ways—with each factor making the other worse.
Implications for Mental Health and Criminal Justice
Seeing the link between TBI and psychopathic tendencies changes how we see and help youth with behavior problems—especially in schools, clinics, and the juvenile justice system.
Opportunities for Intervention
- Thinking and brain tests can find problems with focus and control after TBI.
- Therapy programs, like CBT and DBT, may rebuild emotional control and decision-making skills.
- Care that knows about trauma trains staff to respond to behavior problems with understanding and organized support.
- Combined substance use treatment deals with both the cause and the result, lowering the chances of reoffending.
Instead of calling youth “hopeless,” we can see behavior in a brain-based—and treatable—way.
Prevention Still Matters: Keeping Brains Safe
Preventing TBIs may be the best and cheapest way to lower antisocial problems in youth. Steps to take include
- Enforcing helmet laws and sports safety rules
- Funding programs after school and mentors in high-risk areas
- Teaching about not being violent and solving conflicts in schools
- Teaching families about the long-term effects of head injuries
Also, checking for behavior warning signs early on—especially in places that are underserved—could spot problems before a TBI even happens.
Equity and Inclusion in Future Research
Current research is mostly on male, jailed, and mostly white youth. To really understand how TBI affects psychopathy risk, future studies should
- Include female participants
- Include more racial, ethnic, and income groups
- Use studies over time to see changes as people grow
Research that includes everyone makes sure that new ways to help are relevant, respectful, and work for everyone.
Takeaway: A Brain-Based View on Crime and Compassion
The new link between traumatic brain injury and psychopathic traits helps explain behaviors in troubled youth that we didn’t understand before. Instead of asking, “What’s wrong with this kid?” we start asking, “What happened to this brain?”
Understanding, context, and science-based plans are not just the right thing to do—they’re effective. When we put money into TBI prevention and care that understands trauma, we are not just helping people—we’re making communities safer, improving mental health, and lowering costs for society in the long run.
Suggested Actions for Stakeholders
- Clinicians: Include TBI history in assessments; change therapy to fit thinking and emotional problems.
- Educators: Offer training on trauma and early referrals for possible injuries.
- Juvenile Justice Professionals: Push for brain and thinking evaluations and add rehab to sentencing plans.
- Policymakers: Support money for community outreach, teaching about brain health prevention, and required helmet or safety gear laws.
- Families and Caregivers: Get medical help quickly after any head injury and watch for behavior changes in teens.
A Note of Caution
Not every young person with a brain injury becomes psychopathic. And not every youth showing psychopathic traits has had a TBI. Personality comes from a mix of biology, environment, psychology, and social factors.
Still, knowing more about how brain injury can make someone more likely to have antisocial behaviors gives us a strong way to both prevent problems and give caring help.
Citations
- Milillo, M. M., Neumann, C. S., Maurer, J. M., Jin, C., Commerce, E., Reynolds, B. L., Harenski, C. L., & Kiehl, K. A. (2024). Association Between Traumatic Brain Injury and Psychopathic Traits Among Justice‑Involved Adolescents. Research on Child and Adolescent Psychopathology.
