The Criminal Brain: ADHD, Brain Injuries, Empathy, and Risk

Within psychology and neuroscience, there are theories that examine whether the brain's structure and function may matter for human behavior, including criminality. Research has, for example, shown links between impairments in frontal, temporal, and subcortical brain regions and difficulties with behavioral control, emotional regulation, and social interaction.

Image showing the brain regions?

The frontal lobes and executive functions

The frontal lobe is especially important because it is a part of the brain that helps us plan, make decisions, and control impulses. If this part of the brain functions less effectively, it may become harder for a person to think through the consequences of their actions and to stop impulsive behaviors.

The frontal lobes are responsible, among other things, for executive functions, which is a collective term for the brain's control functions. These functions make it possible for us to plan, keep our attention on a task, control impulses, and adapt our behavior to the situation. If a person has difficulties with executive functions, it may, for example, become difficult to organize schoolwork, follow rules, or manage frustration.

Problems with executive functions and verbal difficulties can contribute to school failure and sometimes also to low self-esteem, which in turn can increase the risk of problematic behaviors.

ADHD, school failure, unemployment, and crime

Difficulties with executive functions occur in neurodevelopmental conditions, for example ADHD. People with ADHD may have problems with things such as attention, impulse control, and planning. These difficulties can make it more challenging to cope with school demands, and research shows that people with ADHD are more likely than others to have difficulty getting or keeping a job, regardless of education level. Both school failure and unemployment can be linked to criminal behaviors.

People with ADHD also have a higher-than-average risk of developing addictions, for example to tobacco, alcohol, drugs, or gambling. People with ADHD are two to three times more likely to be arrested or convicted of crime. In addition, 25% of incarcerated people meet the criteria for ADHD. At the same time, research shows that many of these risks decrease with the right support and treatment, where medication is often an important part.

Studies also show that the risk of being convicted of crime is higher among people with ADHD than in the rest of the population. This does not, however, mean that most people with ADHD commit crime. As in other research, this is about statistical associations, not about the diagnosis itself causing criminality. Difficulties with impulse control and planning may, in some situations, increase the risk of problematic behaviors.

Researchers also emphasize that people with ADHD often have strengths, such as creativity, energy, and originality. With the right support in school and working life, many of the difficulties can be managed, which allows more people to make use of their abilities. It is also important to support whole families, because these problems are often inherited; even relatives of people with ADHD who do not themselves have the diagnosis have an increased risk of being convicted of crime.

Brain injuries and criminality

There are also theories linking brain injuries to criminality. Studies have shown that people who commit crimes more often report that they have previously received blows to the head or experienced situations in which they lost consciousness, which may indicate head injuries. At the same time, it is difficult to determine cause and effect. A correlation does not automatically mean that one thing causes the other. It may, for example, be the case that people who already display more aggressive behavior more often end up in fights and therefore run a greater risk of sustaining head injuries.

Certain brain injuries can affect areas of the brain that are important for impulse control, planning, and social behavior, especially in the frontal lobe. Injuries in these areas can make it more difficult to control impulses, understand social norms, or think through the consequences of one's actions. This may, for example, lead to increased irritability, impulsivity, poorer stress tolerance, or reduced empathy.

The temporal lobe is also important for social and emotional processes. It is linked, among other things, to empathy and the ability to interpret other people's emotions. Injuries in this part of the brain can therefore affect how well a person understands other people's perspectives and feelings.

One example of how the brain can affect empathy is frontotemporal dementia, a disease that affects the front parts of the brain. A typical symptom is that people gradually lose the capacity for empathy. In a study where researchers used brain imaging (fMRI), patients with the disease were shown images that normally evoke compassion, for example images of people experiencing pain. In healthy people, certain networks in the brain are then activated, but in people with frontotemporal dementia the same activation was not seen. This suggests that changes in the brain can affect how we react to the suffering of others. Other conditions in psychiatry that involve a limited capacity for compassion toward others and empathy-related problems include psychopathy.

Overall, the research suggests that changes in the brain can influence behavior, but criminality is a more complex area.

Intelligence and criminality

Another question that is sometimes discussed is whether intelligence is related to criminality. Factors such as school failure and unemployment are clearly linked to an increased risk of criminality, which could suggest that intelligence plays a role.

Research shows, however, that the relationship between IQ and criminality is weak. In meta-studies, the correlation has been found to be around 0.1 for adults and 0.2 for young people. A correlation is a measure of how strongly two factors are related. The value can range from -1 to 1, where numbers close to 0 mean that the relationship is weak. This means that intelligence explains only a very small part of why some people commit crime. Other factors have shown stronger links to criminality, for example future employment opportunities and goals in education. Social factors, such as upbringing, socioeconomic situation, and life opportunities, have in some studies shown a correlation of around 0.5.

At the same time, research suggests that high cognitive ability can function as a protective factor against criminality. A large study from Orebro University, in which researchers followed almost 500,000 men over several decades, showed that people with higher IQ and better psychological resilience had a lower risk of being convicted of crime. This also applied to people who had grown up in more disadvantaged environments, for example with a parent who had been convicted of crime.

The results suggest that abilities such as thinking clearly, handling stress, and cooperating with others can reduce the risk of criminality. Researchers therefore argue that it is important to strengthen children's cognitive and psychological abilities early in life, for example through support in school and other preventive interventions. In this way, the risk of future criminality can be reduced even among people who grow up under difficult circumstances.