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The Brain of a Teenage Killer

Across the country, teenagers arrested and charged with serious crimes are increasingly being tried as adults. For some teenagers, this could mean a mandatory sentence of life in prison without the possibility of parole. This concept is very controversial.

On June 25, 2012, the United States Supreme Court took a stand on the issue. They struck down mandatory life sentences for children 14 years of age and younger. Courts can still impose a life sentence without parole, but it cannot be a mandatory sentence. This allows judges to take other factors into consideration when sentencing teenage offenders.

The basis of the Supreme Court decision was that scientific evidence shows the mind of a 14-year-old is not the same as an adult. The difference is so great that the Supreme Court believes putting a child 14 years old or younger in jail for life, without considering how they ended up in that situation, violates the 8th Amendment. This amendment protects against cruel and unusual punishment.

Why is a teenage brain so different from an adult brain? The answer lies in years of research into cognitive development.

Cognitive development is the study of how the

brain develops higher-order function, such as reasoning, information processing, and decision-making. The brain's ability to perform these tasks changes as a person develops. Think about the difference between a toddler and a person in middle school. The mind of a middle school student can grasp concepts like geometry, literature, and geology. The toddler has a basic understand of shapes (geometry), can listen to stories (literature), and knows where home is located (geography). However, the depth of thinking on these topics is vastly different.

The Supreme Court recently forbade mandatory life sentences for teenagers 14 years old and younger.

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The Brain of a Teenage Killer

The early teenage years are a time of rapid cognitive development. According to Jean Piaget, a founder of the field of cognitive psychology, it is around the age of 12 when people begin to acquire "formal operational thinking." This is the most advanced form of abstract reasoning the brain can achieve.

Some teenagers as young as 12 years old have committed such brutal, violent crimes that they were tried and convicted as adults, rather than as juveniles. If Piaget's assessment is true, by 12 years old some of these children might have had the mental

capacity to understand the severity of their crimes. Essentially, they were tried under the idea that their crimes and brains were adult in nature, so their punishment must also be under adult guidelines.

Yet a growing amount of research indicates that the teenage brain is not as fully developed as previously believed. Scientists are particularly concerned about development of the frontal lobe area of the brain.

The frontal lobe is the area of the cortex involved in decision-making, critical thinking, planning, and other higher-order cognitive functions. This is the area where the brain overrides impulsive behavior. If this area is not totally developed, then impulsive, destructive behavior has a greater chance of occurring.

Scientists now have evidence suggesting the frontal lobe is not fully developed in teenagers. Scientists can scan the brain in a person performing specific mental activities, and create pictures of where there is more and less brain activity.

Consider how the brain processes strong emotions. The frontal lobe is very active in adults, as if their brains are coming up with

The frontal lobe, colored orange here, is responsible for higher-order functions, such as decision-making, critical thinking, and planning.

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The Brain of a Teenage Killer

rational, reasoned responses to the emotion. In the teenage brain, the frontal lobe is not nearly as active compared to the adult brain. This lower activity is linked to lower behavioral inhibition in teenagers, where the brain overrides the "gut reaction" in the response to a situation or emotion.

Other studies show that the teenage brain is not yet fully formed physically. The brain is made of gray matter and white matter. Gray matter is the cell bodies, while white matter is made up of a fatty substance called myelin. Myelin speeds of transmission of signals along neurons. If a neuron has less myelin, it can still communicate; however, the rate of communication is much slower than a neuron with myelin.

Studies on myelination show that the frontal lobe of a teenager is still building up myelin in this part of the brain. In fact, the final, "adult" amount of frontal lobe myelin is not in place until the mid-20s.

For most teenagers, the still-developing frontal cortex leads to impulsive behaviors. For teenagers in a serious situation where critical reasoning is required, the results can be deadly.

Lawyers have successfully used this scientific data to defend their teenage clients against adult penalties when they are convicted of crimes. This data formed the basis for the Supreme Court decision to strike down mandatory sentencing for teenage offenders. This does not mean teenage offenders will not be punished for their crimes. It does mean that judges now have the flexibility to consider the decreased capacity of the teenage brain to reason its way out of a deadly situation.

Myelin is the fatty substance enclosing the neuronal axon. Myelin speeds up transmission of neuronal signals.