The Troubled Teen: Adolescent Neuroscience in the Courtroom

Dr. Robert Kinscherff’s words hung heavy in the air of an overstuffed room at Harvard Law School last fall for a panel on adolescent neuroscience and law. “We may not be able to agree on what to do but we can agree that what we’ve got now is the worst possible option.” Kinscherff, who holds a PhD and JD, is the current Senior Fellow in Law and Neuroscience, a collaboration between the Massachusetts General Hospital and Harvard Law School.

Conversations about juvenile justice, particularly as they relate to the developing brain, can easily become opinion-laden or more ideological than practical. By bringing together doctors, judges, neuroscientists and law professors, Kinscherff hopes the discussion becomes more evidence-based.

The fact that every chair of the room was filled and the walls were lined with bystanders (including myself) attests to the interest and urgency of the topic.

“The adolescent brain is different than the adult brain,” Dr. Leah Somerville, Assistant Professor of Psychology at Harvard University explained. “The overall amount of tissue is not changing. But there are dramatic differences even in the very structure of the brain.”

The details lie between the white matter and grey matter of the brain. White matter is the signal transmission pathway of the brain, like telephone wires that allow a message from one part of the brain to reach another. Somerville explained that during adolescence the overall amount of white matter increases.

By contrast, there is a substantial decline in the brain’s gray matter throughout adolescence. Gray matter is where the action happens. It forms the computational centers of the brain. And it appears that the decline in gray matter during adolescence is really about pruning inefficient connections, resulting in a more efficient adult brain.

The adult brain is a product of both genes and circumstances faced during youth. “The brain does not develop in isolation. Neurodevelopmental trajectories are molded by the environment,” Somerville said. A provocative study conducted by researchers at Rockefeller University determined that orphans in Bucharest, Romania develop smaller brains compared to their non-institutionalized peers in terms of both total cortical grey and white matter. Somerville explained that these highly deprived and highly negative environments can “hijack and stunt the growth of the brain.”

This study is not the only evidence that childhood and adolescent experiences alter brain function. A Harvard Medical School study investigated the integrity of brain regions in adults who experienced childhood sexual abuse at the age of 14 to 16. Researchers found that the prefrontal cortex, which neuroscientists regard as the seat of higher cognitive thinking and decision-making, was negatively impacted and exhibited reduced gray matter volume into adulthood in sexually abused teens. Somerville said this “suggests that the developmental trajectory of the prefrontal cortex is very tenuous during adolescence,” and furthermore that “these effects are not temporary.”


The proper development of the prefrontal cortex, which lies at the front of the brain above the eyes, is essential to reason and decision-making. Image credit: Wikipedia Commons

The circumstances of these studies are somber, but in addition to emphasizing the importance of fostering healthy periods of childhood and adolescence, they also raise concerns for the criminal justice system. The problem at hand is often oversimplified to phrases like “my brain made me do it.” But criminal responsibility is important, and future scientists and judges will need to work together to decide how and when neuroscientific evidence can be used in the courtroom to determine a criminal’s level of control when they committed the crime.

Neuroscience evidence is not all straightforward, however. For example, two people with similar brain scans can easily exhibit different behavior. On average, a certain trait or characteristic of a person’s brain biology may be correlated with a certain behavior, but not always. Retired Judge Nancy Gertner said, “All of these averages seem to suggest that we know a great deal about the children that we are sentencing,” implying that this is obviously not the case.

Improved understanding of the physical and cognitive differences between adolescents and adults led the Supreme Court to pass rulings protecting minors from capital punishment and life without parole. In 2005, Roper v. Simmons, the court ruled capital punishment unconstitutional for convicts younger than 18-years-old. The court wrote, “As any parent knows and as the scientific and sociological studies…tend to confirm, a lack of maturity and an underdeveloped sense of responsibility are found in youth more often that in adults.”

In 2010, Graham v. Florida, the Supreme Court extended protections for youth declaring that life without parole in cases other than homicide is deemed unconstitutional for people younger than 18-years-old, saying that, “Developments in psychology and brain science continue to show fundamental differences between juvenile and adult minds.”

The 2012 Supreme Court case of Miller v. Alabama eliminated the life-without-parole option for people under 18 years of age, even in cases of homicide. The court wrote, “It is increasingly clear that adolescent brains are not yet fully mature in regions and systems related to higher-order executive functions such as impulse control, planning ahead, and risk avoidance.”

After all the discussion, Kinscherff, Somerville, and Gertner agreed that moving forward won’t be easy, especially since “adolescence” is a continuum. Even though 18-year olds are considered legal adults, adolescent brain development continues past this age. “There is no magical point at 18 which distinguishes it,” Kinscherff said.

“Treating youth as adults doesn’t always work very well,” Kinscherff explained. “Most kids incarcerated on adult conviction are home by 26 years of age. And they are gonna be back. Youth treated as adults tend to come back more rapidly with a more serious crime against a person.”

Judge Gertner said, “It is easier to generalize and imprison than anything else.” Practically applying neuroscience to the law is no easy task, but the panelists think doing so may someday allow for a more just legal system.

Judge Gertner concluded the discussion on a heavy but important point, saying, “On one side we have a judge saying give this child a break he was abused, and on the other side you have a judge saying the very fact that he was abused is why we cannot trust him to be free.”

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