Facts or Fictions about the Teenage Brain: Is it all gasoline, no brakes?

By Karen CastagnaPedal to the Metal tricycle

Teenagers are known to act in famously reckless ways. They put the pedal to the metal and floor the gas, experiment with drugs and play with guns. Some, like these teenagers in Riyadh driving a Bentley all the way to 300kph, go too fast.

The jump from training wheels to high speed can be drastic. According to Centers for Disease Control and Prevention figures, more than 16,000 young people die each year in the U.S. from unintentional injuries.

The most commonly quoted explanation for teens’ carelessness is that their brains just aren’t developed enough to know better. But new research suggests that in the case of some teens, the culprit is just the opposite: the brain matures not too slowly but, perhaps, too quickly.

In a paper published in PLoS ONE a team led by psychiatrist Gregory Berns of Emory University in Atlanta showed that adolescents who engage in more dangerous activities have white-matter pathways that appear more mature than those of risk-averse youths.

Their research found the direction of correlation suggests that rather than having immature cortices, adolescents who engage in dangerous activities have frontal white matter tracts that are more adult in form than their more conservative peers. White matter, essentially the brain’s wiring, forms the neural strands that connect the various gray-matter regions. Maturation of white matter is important because it increases the brain’s processing speed; nerve impulses travel faster in mature white matter (Berns, Moore & Capra 2009).

What to make of this? Certainly these variable patterns of maturation have consequences.

B.J. Casey, neuroscientist at Sackler Institute, writes about the paradox of preventable deaths for human adolescents (Casey & Caudle 2013). At a time when a person is stronger, has higher reasoning capacity, is faster and more resistant to disease (cancer or heart disease), there is such an increase of accidental fatalities-automobile accidents, suicides and homicide. Casey presents evidence that underscores the importance of considering brain regions as part of a developing circuitry that is fine-tuned with experience during this time.

Preventable forms of death (accidental fatalities, suicide, and homicide) [are] associated with adolescents putting themselves in harm’s way, in part because of diminished self-control—the ability to suppress inappropriate emotions, desires, and actions. This article highlights how self-control varies as a function of age, context, and the individual and delineates its neurobiological basis.

What were they thinking…..or not?

As I began my research on families, adolescence and the juvenile system, I came across an episode where ten senior boys (the majority with pending college scholarships) trespassed on to school property at 3 am and toilet papered the entire school. Taking into account the zero tolerance school discipline policy, the boys’ scholarships would have been taken away, just like that…

But the prank was deemed innocuous, something that most school kids do at some point in their immature adolescent years. It was reported the boys acted on a whim after studying together for a final exam, and wanted to do something so their class would remember them. The school considered these boys to be “good kids,” and they were able to work off their punishment through the in-school suspension program.

Other kids I work with, often young minority men coming from tougher backgrounds, don’t get that same “benefit of the doubt,” particularly if they have had run-ins with authority figures before. What might also be whims for them can be taken as something more serious, an indication that they are on the road to being bad kids and that they need to be punished to keep them from “making the same mistake twice.”

What is The Big Picture? Let’s take selfies at adolescents’ brains to find out!

In the last 15 years, new imaging technology called Magnetic resonance imaging (MRI) and functional MRI (fMRI) without the use of ionizing radiation, has facilitated a rapid expansion of a new field, developmental cognitive neuroscience. MRI and fMRI provide snapshots and records brain activity to investigate maturational changes in the brain. Also during this time, there are other changes in the brain, in other regions including the parietal and temporal cortices as well as the cerebellum (Steinberg 2011).

From this expansion of studies, it is well established that brain maturation occurs through adolescence, with some of the most significant changes are in the prefrontal areas, otherwise known as the prefrontal cortex (PFC). In the PFC, during adolescence there is a decline in grey matter (made up of the cell bodies of neurons, the nerve fibers that project from them and support cells) and an increase in white matter. The basic notion is that both these things are happening at the same time during adolescence.

The density of prefrontal gray matter follows a bell shaped curve with a peak around age 11 for girls and later for boys. There is massive brain reorganization between 12-25 yrs old, and shows up as dramatic changes in adolescent brain development. Particularly in the fiber tracts that link different brain regions and structures (Steinberg 2011). The increase in structural connectivity is not surprisingly paralleled by an increase in functional connectivity, which has significant implications in adolescent behavior especially with regard to cognitive control.


“You really need a haircut”

Synaptic pruning takes place in adolescent brains-heavily used synapses grow stronger and little used ones wither away. This pruning of neural pathways and synapses is linked to changes in behavior, environment and neural processes, (Pascual-Leone, et al 2011). For example, in mice models, synaptic pruning is experience-dependent and pruning in human adolescents has been linked to better performance on cognitive tests (Yu, Xinzhu, et al. 2013).

What is not known is just how much of the synaptic proliferation and elimination is contextually dependent, and if so then we should expect to see brain differences linked to differences in experience. We do know the quality of each individual’s social environment can have profound influences on the development and activity of neural systems, with repercussions on a variety of behavioral and physiological responses (Curley et al. 2011). Given this research, changes in brain plasticity in adolescents living in dysfunctional environments are likely to be distinct from the changes of those in protective and supportive ones (Pascual-Leone, et al 2011).

“I hate those jeans Mom got for me”

There are studies that contradict each other in the areas of structural and functional connectivity that link the development of resistance to peer influence to improvements in the coordination of emotion and cognition. One study suggests individuals with highly organized white matter are less likely to be drawn to immediate rewards (Olson, et al 2008). Yet another report indicates structural maturity of white matter are associated with more risk-taking, not less (Berns, et al 2009). It is too early to render an explanation for the inconsistency (Steinberg 2011).

Part of the problem is that brain researchers only see the brain as what is changing during adolescence. But much more than that changes as children mature. Research suggests that in many cultures from a global perspective, development does not correspond exactly with adolescence as a separate and distinct category of the ages 10 to 19 years of age. For example, in Bangladesh, childhood is different for those children attending school without economic responsibilities, while children who enter the workforce are no longer considered children when they begin to work. Among the Hmong people, there is no middle transitional stage between childhood and adulthood at ages 11 or 12. If there is a transitional period of the life cycle, analogous to adolescence, it is not normative across cultures (Choudhury 2010).

Adolescence and Juvenile Justice-To toilet paper the school or not to toilet paper, what would the adolescent mind do?

After a decade of declining juvenile crime rates, the moral panic that fueled the “get-tough” reforms of the 1990s and early 2000s—reforms that eroded the boundaries between juvenile and criminal court and exposed juvenile offenders to increasingly harsh punishments —has waned. In a 2008 Princeton-Brookings report on the future of children, in the section on Juvenile Justice, state legislatures across the country have reconsidered punitive statutes that were enacted not so many years ago. What appears to be happening now is a pendulum that has reached its apex and is slowly beginning to swing back toward more moderate policies, as some politicians and the public have become disillusioned with the high economic costs and ineffectiveness of the punitive reforms and the harshness of the sanctions (Rouse, Brooks-Gunn & McLanahan 2008).

The adolescent phase involves a lot of experimentation, which for many adolescents means engaging in the risky activities we have described, including involvement in crime. Self-report studies have found that 80–90 percent of teenage boys admit to committing crimes for which they could be incarcerated (Moffitt 1993). But the typical teenage delinquent does not grow up to be an adult criminal. The statistics consistently show that seventeen-year-olds commit more crimes than any other age group—thereafter, the crime rate declines steeply (Scott & Steinberg 2008).

Several developments have converged to change the direction of the nation’s youth crime policy. Among the most important was the steady decline in juvenile crime beginning in 1994. In response to these changes, Scott and Steinberg argue that it is appropriate to reexamine juvenile justice policy and to devise a new model for the twenty-first century. Substantial new scientific evidence about adolescence and criminal activity by adolescents provides the building blocks for a new legal regime superior to today’s policy. The argument is to place adolescent offenders into an intermediate legal category—neither children, as they were seen in the early juvenile court era, nor adults, as they often are seen today. This approach is not only more compatible than the current regime with basic principles of fairness at the heart of the criminal law, but also more likely to promote social welfare by reducing the social cost of juvenile crime (Scott & Steinberg 2008).

teens at concert with dayglow paint

“You’re Just Jealous”-Youth Envy

Taking risks give adolescents heightened feelings and for some boys taking part in a mock “fight club” is the best, for other teens, covering your body with dayglow paint and dancing at a concert is a thrill. During adolescence, teens are the quickest they will ever be, crushes will never be better and the thrills won’t ever be quite the same (Casey & Caudle 2013). Evidence is growing concerning significant changes in subcortical processes during adolescence (this is where the hippocampus, amygdale, striatum are; also called the limbic system where emotion and memory reside; the middle brain that coordinates body movement and inhibits a person’s behavior in a complex social situation). Especially important are increases in dopaminergic activity during adolescence linking limbic, striatal and prefrontal areas. Dopamine functions as a neurotransmitter and plays a major role in reward-motivated behavior (Dahl & Forbes 2011).


Some people write of adolescents as all gasoline–is that right?

No. That mischaracterizes the brain research. There are more subtle changes happenings: 1) the ratio of gray to white matter in prefrontal areas; 2) the increase in structural connectivity and increases in functional connectivity has significant implications with regard to cognitive control; 3) and the increase in dopaminergic activity in the pathways between the prefrontal-striatal-limbic regions. Together these provide a framework for a theory linking brain maturation in adolescence to greater susceptibility to risky behavior (Steinberg 2010).

Let your teen build their own brain but remain close

In my experience as a parent of teenagers and also someone who does research on adolescence, I do want to say your teen needs you, and deep down wants to be with you and values your opinions. Stress, fatigue or challenges can cause a misfire. Parents and other adults can be great sideline leaders-as conductors, coaches, and cheerleaders. Neuroscientist, B.J. Casey says you just have to know when to pull back and let the teen do the work. Until then, parents need to know that the science shows they really can influence their children’s brain development.

“From imaging studies,” Jay Giedd writes in his review article, “one thing that seems especially intriguing is this notion of modeling . . . that the brain is pretty adept at learning by example. As parents, we teach a lot when we don’t even know we’re teaching, just by showing how we treat our spouses, how we treat other people, what we talk about in the car on the way home. . . . Things that a parent says in the car can stick with them for years. They’re listening,” he said, “even though it may appear they’re not.” So, what can we do to change our kids? “Well, start with yourself in terms of what you show by example,” Giedd advised.

Taking care of our brains is important at any age, so while our teens are watching our behavior and the things we do, learning a new skill together that has some thrill seeking element would be a good thing and a bonding experience too. I’m thinking of asking my teenager of doing an Autocross with me, an extra benefit would be learning how to handle a car at high speed. My job is to let my teen develop his own brain, but I’m going to be there waiting for the moment when he says to me-“Mom, I’ve been thinking about …., what do you think?” I’ll be there with my mom hat on!

Suggested videos

Explaining what is happening in the teen brain in a humorous way, including clips of James McEnroe shouting at the umpire and throwing down his tennis racket

Explaining the teenage brain, suitable for a classroom, by Pandas Smith

Dr. Barbara Strauch (medical, science and health editor for the New York Times) pitching her book, “The Primal Teen,” explains the latest research, October 26, 2010.

When does a person really become a ‘grown up?’ Surely age can’t be the only determining factor. Laci Green looks at how the brain matures and what it means- from a scientific perspective- to be an adult in a news show format, Published on Dec 8, 2013

References cited:

Berns, Gregory S., Sara Moore, and C. Monica Capra
2009 Adolescent Engagement in Dangerous Behaviors is Associated with Increased White Matter Maturity of Frontal Cortex. PloS One 4(8):e6773.

Blakemore, Sarah-Jayne
2012 Imaging Brain Development: The Adolescent Brain. Neuroimage 61(2):397-406.

Casey, BJ, and Kristina Caudle
2013 The Teenage Brain Self Control. Current Directions in Psychological Science 22(2):82-87.

Casey, B. J., Sarah Getz, and Adriana Galvan
2008 The Adolescent Brain. Developmental Review 28(1):62-77.

Choudhury, S.
2010 Culturing the Adolescent Brain: What can Neuroscience Learn from Anthropology? Social Cognitive and Affective Neuroscience 5(2-3):159-167.

Choudhury, Suparna, Kelly A. McKinney, and Moritz Merten
2012 Rebelling Against the Brain: Public Engagement with the ‘neurological Adolescent’. Social Science & Medicine 74(4):565-573.

Curley JP, Jensen CL, Mashoodh R, Champagne FA
(2011) Social influences on neurobiology and behavior: epigenetic effects during development. Psychoneuroendocrinology 36(3):352–371

Dayan, Jacques, Alix Bernard, Bertrand Olliac, Anne-Sophie Mailhes, and Solenn Kermarrec
2010 Adolescent Brain Development, Risk-Taking and Vulnerability to Addiction. Journal of Physiology-Paris 104(5):279-286.

Giedd, Jay N.
2008 The Teen Brain: Insights from Neuroimaging. Journal of Adolescent Health 42(4):335-343.

Moffitt Terrie
1993 “Adolescence-Limited and Life-Course-Persistent Antisocial Behavior: A Developmental Taxonomy,” Psychological Review 100 (1993): 674–701.

Pascual-Leone, A., Freitas, C., Oberman, L., Horvath, J. C., Halko, M., Eldaief, M. et al.(2011). Characterizing brain cortical plasticity and network dynamics across the age-span in health and disease with TMS-EEG and TMS-fMRI. Brain Topography, 24, 302-315. doi 10.1007/s10548-011-0196-8

Rouse, Cecilia Elena, Jeanne Brooks-Gunn, and Sara McLanahan
2005 Introducing the Issue. The Future of Children 15(1):5-14.

Scott, Elizabeth S., and Laurence Steinberg
2008 Adolescent Development and the Regulation of Youth Crime. The Future of Children 18(2):15-33.

Steinberg, L.
2010 A Behavioral Scientist Looks at the Science of Adolescent Brain Development. Brain and Cognition 72(1):160-164.

Yu, Xinzhu, Gordon Wang, Anthony Gilmore, Ada Xin Yee, Xiang Li, Tonghui Xu, Stephen J. Smith, Lu Chen, and Yi Zuo
2013 Accelerated Experience-Dependent Pruning of Cortical Synapses in< i> Ephrin-A2 Knockout Mice. Neuron 80(1):64-71.

Yurgelun-Todd, Deborah
2007 Emotional and Cognitive Changes during Adolescence. Current Opinion in Neurobiology 17(2):251-257.

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