Adolescence is an Age of Opportunity
By Lydia Denworth | May 2021 | Scientific American | Topics: Brain, Learning, Parenting and Family, Science and Health
Advances in neuroscience and psychology could lead to real-world benefits in education and mental health
Here is a parable for our time: There once was an adult who wanted to encourage eighth graders to eat healthier food. The adult designed a lesson plan full of nutritional information—why fruit and vegetables are good for you, why junk food is bad for you, and so on. A similar approach had worked with younger children. But the eighth graders declared the intervention—and, if we’re being honest, the adult—boring. They carried on eating junk food, some of them in greater quantities than they had before.
Versions of that story play out in real life all the time, although the age of the adolescents varies, and the goal could be anything from reducing bullying or depression to increasing engagement with math. With discouraging regularity, researchers find that what works with younger children is no longer effective with adolescents. Eighth grade seems to be the inflection point.
If we thought more carefully about what it is to be an eighth grader, however, down to the level of changes in the brain, our parable could have a happier ending. Thirteen-year-olds are concerned with status and respect—these kids do not want to feel patronized by adults. In a study published in 2019 in Nature Human Behaviour, instead of nutritional information, researchers showed more than 300 eighth graders in Texas investigative reports revealing that food company executives use unhealthy ingredients, target young adolescents in their marketing, and won’t let their own children eat their products. The students were outraged and began to see healthy eating as a way of taking a stand against being manipulated. For the next three months the students made healthier snack purchases in the cafeteria. And in a follow-up study, the researchers found that the students, especially boys, with higher levels of testosterone (a marker of pubertal maturation in both boys and girls) were most likely to respond well to the intervention.
Over the past 15 years neuroscience has dramatically changed our understanding of the structural and functional changes in the brain during adolescence, which runs from around the age of 10 all the way into the mid-20s. It is a time of rapid brain growth and neuronal fine-tuning when young people are especially sensitive to social cues and rewards. More recent research has focused on how the adolescent brain interacts with the social environment. It shows that social context and acceptance strongly influence behavior. Adolescence might even constitute a sensitive period for social and emotional learning, a window of time when the brain is uniquely primed by neurochemical changes to make use of social cues for learning.
A growing group of researchers and clinicians see these neuroscientific findings as a chance to do things differently. When a young brain is looking for experience, teachers, parents and other influential adults should seek to capitalize on the richness of learning and stave off negative experiences such as smoking or drug use. This was a central idea in the 2019 National Academies of Sciences, Engineering and Medicine report on the promise of adolescence, which called for investments in programs and interventions that use the brain’s capacity to change during adolescence to promote beneficial shifts in young people’s life trajectories.
A sensitive period for social and emotional processing also suggests that certain phases of adolescence may be more opportune than others for certain approaches. Early adolescence in particular—from roughly age nine to 11—could be an opportunity to launch kids on a positive path by buttressing their sense of self and motivation to learn. The nutrition experiment shows the benefits of fine-tuning interventions for middle adolescents, who have been through puberty. And no one wants to suggest that it’s ever too late to help young people in trouble, especially given that the most serious behavioral and health problems of adolescence tend to occur at 16 and beyond.
To meaningfully compare the results of which interventions work best at age 10 or 14 or 18 requires extensive longitudinal studies, which have not yet been done. Even so, the advances in developmental science appear poised to lead to wiser, more effective approaches to supporting young people’s education and physical and mental health. These new methods emphasize adolescents’ concern with status and respect, their evolving sense of self in relation to the wider world, and their need to contribute and find purpose. Similar ideas already underpin the growing interest in social and emotional learning among educators. Rather than focusing on the storminess of the teenage years, these ideas offer a sunnier view of adolescence as a window of opportunity.
For decades much of the research on adolescence focused on its dark side. Although those years are the physically healthiest period in life, when strength, speed, reaction time, reasoning abilities and immune function all improve or peak, adolescence also brings alarming increases in rates of accidents, suicide, homicide, depression, alcohol and substance use, violence, reckless behaviors, eating disorders, obesity and sexually transmitted disease compared with the rates for younger children.
But a different interpretation of adolescence emerged in the 2000s, stemming from two important new findings. Neuroscientists showed that puberty ushers in a period of exuberant neuronal growth followed by a pruning of neural connections that is second only to the similar process that occurs in the first three years of life. They also showed that the maturation of the adolescent brain is not linear. The limbic system, a collection of brain areas that are sensitive to emotion, reward, novelty, threat and peer expectations, undergoes a growth spurt while the brain areas responsible for reasoning, judgment and executive function continue their slow, steady march toward adulthood. The resulting imbalance in the developmental forces helps to explain adolescent impulsivity, risk taking, and sensitivity to social reward and learning. From an evolutionary sense, much of adolescents’ behavior pushes them to leave the safety of family to explore the larger social world—a step on the way to becoming independent adults.
Another line of research, from the human connectome project, shows that adult brains vary in their patterns of neural connections throughout the brain, whereas children’s connectomes are less distinctive. Those differentiated patterns of connection emerge in adolescence—between the ages of 10 and 16, just when social values and cognition are developing quickly. And the changes in the connectome data show up on average a year to a year and a half earlier in girls than in boys, just like puberty does, which suggests that the two things are intertwined.
The idea that adolescence might constitute a sensitive period for social and emotional processing was put forward in 2014 by neuroscientists Sarah-Jayne Blakemore and Kathryn Mills, now at the University of Cambridge and the University of Oregon, respectively. Previous research had assumed that social-cognitive abilities such as theory of mind were mature by the middle of childhood, but Blakemore and Mills laid out the many continuing changes across adolescence in social cognition and the network of brain regions governing social behavior.
Sensitive, or critical, periods are windows of time when the brain is primed to make specific neural connections that depend on the input received. They are timed to when important information is available and most useful for development. For sensory processing such as vision and hearing, such periods are well defined with an opening, peak and closing. A brain deprived of sight or sound early in development will never be able to see or hear normally. Likewise, a sensitive period for language acquisition explains why people who learn a foreign language after puberty typically have an accent. Sensitive periods for social learning have been harder to pin down.
Animal research has identified some versions of sensitive periods for social learning. Songbirds can delay the closing of the sensitive period for vocal learning if they need more time to learn their songs, which usually happens in adolescence. “It’s a gorgeous example of a sensitive period for learning that has social function,” says Linda Wilbrecht of the University of California, Berkeley, who has studied sensitive periods in songbirds, mice and humans.
Neuroscientist Gül Dölen and her colleagues at Johns Hopkins University identified an adolescent critical period in mice for something called social conditioned place preference (social CPP). The research followed up on an observation by the late Estonian neuroscientist Jaak Panksepp. He presented mice with two different kinds of bedding—on one, the mice were alone; on the other, they were with friends. When the mice subsequently had a choice of bedding, adolescents, in particular, showed a preference for the bedding that carried a memory of friends.
Dölen ran similar experiments with roughly 900 mice at 14 different ages and mapped out exactly when this preference for place occurs. Triggered by changes in oxytocin that lead to increased synaptic plasticity, it peaks 42 days after birth (roughly age 14 in humans), when the mice become sexually mature. “It’s a really important stage of their lives when they’re leaving the nest and trying to create their own groups,” Dölen says. “[In] that window of time, when they’re really sensitive to what other members of their group are doing, when they’re learning from their group, when they’re forming attachments to the group—that’s when that peaks.” It seems the brain is suddenly alert to and rewarded by information that it had previously ignored. “There’s information flowing by us all the time,” Wilbrecht says. “Once puberty and hormones pass through the circuit, suddenly those cues have meaning. They don’t have salience until you shift into the adolescent phase.”
PRIMED FOR LEARNING
These windows of rapid change create both learning opportunities and vulnerabilities. What adolescents are learning is all-important. “The adolescent brain is primed for social and emotional learning, to explore, to interact, to take chances so they can learn, but it all depends on what we do to give them scaffolded opportunities in order to learn,” says psychologist Andrew Fuligni of the University of California, Los Angeles. Harmful experiences may lead to negative spirals from which it’s hard to recover. Research has shown that earlier experimentation with alcohol and drugs makes an adolescent more likely to become addicted.
“When your brain is going under rapid reorganization, that’s probably not the best time to introduce external chemicals,” says developmental psychologist Anthony Burrow of Cornell University. “Your body and brain are paying attention in a slightly different way. [Your brain is] going to organize itself around what you’ve done to it at that particular moment.”
Protective factors in the adolescent’s environment could support positive trajectories. What do protective factors look like? They include supportive relationships with family and caretakers and access to resources such as scaffolded opportunities to learn in positive ways. They also include some elements that have previously been underappreciated. Fuligni’s research shows that adolescents have a need to contribute to society and that doing so makes them feel valued and can safeguard against anxiety and depression. “Part of what the brain is designed to do during the teenage years is to learn how to contribute to the social world,” Fuligni says. This need is particularly significant in adolescence, he argues, because it’s a time when the social world is expanding and young people are becoming capable of “making contributions of consequence.” These contributions can occur within peer groups, the family, or at a larger societal level. It’s no accident that recent social protest movements for gun control and against structural racism have been led in large part by young people.
The specifics of what today’s adolescents are learning—and what they are not—may bear on the alarming rises in depression, anxiety and suicidal ideation at that age compared with earlier ages (as well as with previous generations). Some of the information they encounter about mental health may be amplifying their problems, says psychologist Nicholas Allen of the University of Oregon. He points to the controversial Netflix series 13 Reasons Why, which included a detailed depiction of a character’s suicide and which research suggests was associated with an increase in adolescent suicides. “Whether it’s a supportive, solution-oriented discussion or whether it’s a ruminative, hopeless discussion will have a big effect,” Allen says. “Too often adolescents who are tending toward depression, anxiety or suicidal ideation have a tendency to ruminate, and they find friends—both online and offline—who feed that tendency rather than help the teenagers move beyond it.”
There is still debate about how best to use the new neuroscientific knowledge to help adolescents. “We’ve learned an enormous amount about the brain, but the application of that knowledge is not straightforward,” Allen says.
A big question is when to intervene. One argument for zeroing in on early adolescence is to act preemptively. Because so many of the problems of adolescence occur in the mid- to late teenage years, many interventions target that time. “If you’re a developmentalist, that is too late,” says Ronald Dahl, a pediatrician and developmental scientist and founder of the Center for the Developing Adolescent at U.C. Berkeley. “Smaller, more subtle, positive interventions earlier are probably a much more promising way to improve population health.” The logic of that idea first struck Dahl when he was still practicing as a pediatrician. At conferences, he started mentioning the importance of reaching kids early and found educators nodding their heads. They introduced Dahl to the idea of the fifth grade slump and the eighth grade cliff, a phenomenon in which children’s disengagement with education starts slowly with a dip in grades and participation around fifth grade, when most students are 10, and accelerates so that those same students are failing three years later.
The neuroscience also suggests that acting early could make sense. “What we’re increasingly learning is that there’s another node of new plasticity around the time puberty starts,” Dahl said at a conference in early 2020. “We talk about this as a high-stakes pivotal transition in terms of patterns that are beginning to be shaped.” In a study in Tanzania, Dahl and his colleagues succeeded both quantitatively and qualitatively in reducing ideas of gender inequality among 10- and 11-year-olds with a series of technology lessons at which girls were as likely to shine as boys.
Others are wary of focusing too much on any one phase. They emphasize that what neuroscience contributes to the discussion is a reminder of what to prioritize. “What is the thing at this stage of life that is most plastic, that is open for input? That tells you where the risk is, but it also tells you where the opportunity is,” Allen says. “What the brain science says is that you should be looking in this area: social and emotional learning.”
It is not surprising then that those interventions that look most promising take into account adolescents’ desire for status and respect, as well as their need to contribute and find a sense of purpose. According to Fuligni, the most successful volunteer programs give adolescents a say in what to work on and a chance to reflect on the work, and the projects also feel meaningful. Meaning seems to matter in other efforts, too. In a study of early adolescents participating in a 4-H program, Burrow found that those who were asked to write about their sense of purpose before engaging in an educational activity were more likely to engage with the activity and find it important and interesting. “Purpose is a pretty powerful form of identity capital because it’s not just an answer to the question of who you are, but it’s an answer to the question of who you’re going to be and the direction you’re heading in,” Burrow says. “It’s got legs.”
Psychologist David Yeager of the University of Texas at Austin has been exploring how best to frame messages to teenagers and studying whether their effectiveness interacts with pubertal maturation, a sign that the neurochemical changes are playing a role. “You should be able to show that if you communicated respectfully to teenagers in a way that felt authentic and supported their autonomy and independence, you should have bigger effects for adolescents, especially if they’re more mature in terms of their puberty,” he says.
So far his research bears that out. One series of experiments showed that the way you frame a request to take medicine predicted different rates of compliance and furthermore that those rates varied with testosterone levels. Some 18- and 19-year-olds came into the lab and were given instructions in a condescending way: I’m the expert, I know what’s good for you, take this. Another group of young adults were given instructions in a more respectful manner: Let me explain the reasons this medicine can be useful.
For ethical reasons, the medicine in question was actually a spoonful of Vegemite, a notoriously unpleasant-tasting vitamin supplement. Asked respectfully, people were twice as likely to take the Vegemite. Furthermore, participants with higher testosterone levels were significantly less likely to take the medicine in the disrespectful condition and more likely to comply in the respectful condition. When Yeager and his colleagues manipulated testosterone levels with a nasal inhaler, they found that doing so made individuals with naturally low testosterone levels behave just like those with naturally high testosterone levels.
While the medicine study was a nice test of how respectfulness might matter, Yeager says that the 2019 nutrition study informing eighth graders about unsavory food industry practices, which he helped lead, is even more promising. “That’s the first direct evidence that these pubertal hormones sensitize you to status and respect and therefore change the way you respond to health messages,” he says. “And not just how you respond in the moment but the way you internalize them and continue to keep acting on them after the treatment is over.”
In other words, now we know more about what causes adolescents to put up a wall and resist attempts to change their habits, beliefs and ways of coping. That same knowledge offers ways to break down that wall. “It’s only recently that we know how to work with those sensitivities and not against them,” Yeager says. “I’d like it to be a wake-up call for adults who work with kids.”
This story was produced with support from the Education Writers Association Reporting Fellowship program.