Dr. Jensen | Transcript Page 1 of 7

The Power of the Adolescent Brain: A TAG Talk

Transcript — Full Length

Frances Jensen:

Hi, I'm Doctor Frances Jensen, and I'd like to talk to you today about the teen or adolescent and young 

adult brain. Aside from being a neurologist and a neuroscientist working on brain development, I am 

also the mother of two teenage sons, and I watched them change dramatically as they passed from 

childhood into adolescence. This led me to look at what is going on with the teenage brain, what's the 

new literature, what's the new research. 

What I found was that until very recently, little was known about the teenage brain. Work had been 

done on early life changes and also on the aging brain, but this middle ground had been less studied. In 

the past decade, we've learned that the brain is the last organ in the body to reach full maturity, and 

therefore in the adolescent period it is not done yet. 

Two major things are different about the adolescent brain. One is that our brain regions connect 

together by tracks, but that process doesn't complete until your mid-to-late 20s. It's start from the back 

and goes to the front, so the last part of your brain to reach full connectivity is your frontal lobe, and the 

frontal lobe is there to suppress impulses, suppress risk taking, make decisions, organization, judgment, 

empathy. All things that adolescents tend to be challenged by. 

The other part of science is that we now know that each brain region itself is actually more active in 

childhood and adolescence than it will be later in life. Their capacity to learn is higher in adolescence 

than it is later in life. So, this is an actual wondrous time in development, where people can learn faster. 

In fact your IQ can even change in the adolescent years. 

Our brain cells learn by increasing the strength of connections between them at a place called a 

synapse, and in fact children and teenagers have more synapses than adults, so they have more of the 

machinery to actually learn with. This is positive because it means that you can learn and work on your 

strengths and correct your weaknesses during adolescence, but it also suggests that their brains may be 

vulnerable to the effects of negative, not just positive things. This is basically increasing our 

understanding of how the adolescent brain is more vulnerable to addiction or to the effects of 

substances of abuse or even stress during this window. 

Regions of our brain connect to each other through connections that actually have to be insulated like a 

wire would be insulated to have fast connections, fast real-time connections. This process is a wrapping 

process that we insulate our connections with something called myelin. The myelination of the brain 

takes almost two and a half decades. Hence, the last place it's connected, since it's going from the back 

to the front, is the frontal lobe, and this is where teenagers and adolescents have less connectivity 

relative to adults. Hence, they don't necessarily have the ability to have real-time access for decision 

making, impulse control, judgment and empathy. 

I will talk more about teen behavior, addiction, metal health, and how parents and other adults can 

apply this knowledge to their interactions with adolescence. 

Hi, I'm Doctor Frances Jensen, I'd like to talk to you today about teen and adolescent brains, and how 

brain development relates to risky behavior. 
Dr. Jensen | Transcript Page 2 of 7

We've learned a lot about how neurobiology is explaining why teenagers have issues with risk taking, 

impaired decision making at times, and the inability to consider consequences of some of their actions. 

This can be vexing for adults, but there's really neurobiology behind this. The process of connecting the 

brain, connecting the part of the brain, the frontal lobe, which is responsible for impulse control and 

decision making, has not yet completed by adolescent years. 

While the lack of connectivity, of full connectivity of the frontal lobe may be a vulnerability of the 

teenage brain, the teenage brain also has a great strength and that is that a teenager can learn faster 

than adults. Their synapses, parts of the brain where our neurons, our brain cells are connecting to one 

another, are more active and we use them to learn. Because teenagers have this extra strength in 

learning, they are learning machines. We could try to use that to help them learn cause and effect, while 

their frontal lobe is still coming online if you will. 

Studies show that adolescents react more strongly to reward and risk than adults and children. Actually, 

the novelty seeking area of their brain, the reward center, is actually more active in adolescents 

compared to adults and children. Neuroscientists believe that the revved up response to reward and the 

underdeveloped impulse control, meaning the lack of full connectivity of their frontal lobe, really 

contribute to this greater risk taking behavior seen in teens and adolescents. 

Most people respond negatively when you combine the word teen and risk-taking. We all know the 

negative risks we want to teens to avoid. Smoking, drinking, drugs, driving too fast, texting while driving, 

and a myriad of other poor choices that they can make. We often forget that teen and young adult life 

also requires some aspect of novelty seeking and positive risk taking, starting with your first job, 

volunteering in the community, going off to college, having your first romantic relationship, managing 

your own money, renting your first apartment. These are all positive risks that teens and young adults 

should take and learn from. It is truly a process of trial and error that shapes our brains. 

The trick is pointing out their natural tendencies towards positive risks, and understanding that teens 

may need what we call a frontal lobe assist from the adults around them at times. Adults can help teens 

with thinking through their positive and negative consequences of some of their decision, before and 

after they take action. 

Focusing on the positive aspects of teens risk and behavior may be more important as highlighting the 

negative parts. Adolescents have energy and enthusiasm, and they can learn so fast, that we can use this 

very positively. Teens are open to new experiences and intellectual challenges, more than they will later 

in life. They're ready to try new things, work to overcome obstacles and difficulties, and they will learn a 

great deal in this process. 

All of this helps build positive self-concept, confidence, and independent living skills. 

We've learned a lot about brain development in recent years. We know the brain is very different during 

teen and young adult years compared to later adulthood. We know that enriching positive experiences 

have lasting impact at this age, because of their ability to mold their brain to experiences. However, we 

also know that negative inputs can mold the brain also. Addiction is an example of this. Addiction is 

essentially a form of learning, but in the reward circuits in your brain. Just as adolescents can learn 

faster and build stronger connections when they're learning, unfortunately they can get addicted faster, 

because really they're just using the same process of learning but in the addiction circuit if you will. 

Hence, adolescents can get addicted harder, stronger, longer, faster than an adult for a given exposure 

to a substance of abuse. This is paired of course with the fact that their frontal lobes, which is their 
Dr. Jensen | Transcript Page 3 of 7

impulse control center, haven't been fully connected for fast access at this point in life. So, the risk 

reward parts of the adolescent brain are very active at a time where the frontal lobe, which normally 

suppresses and inhibits impulses, is not yet fully online if you will. 

The big problem with the adolescent brain, because it's growing so rapidly, is chronic substance abuse. If 

a drug is being present across periods of time in the adolescent brain, damage can be done that may be 

irreversible. Both animal and human studies are showing an effect of chronic daily exposure to cannabis 

on later brain IQ and cognitive function. 

Cannabis can affect synapses and how they function. It can also impair learning, and research has shown 

that cannabis can affect the way the brain wires itself during development if there is chronic exposure. 

Some studies have shown that actually the connections to the frontal lobe, which are involved in 

decision making, seem to be less strong in people that have smoked marijuana during the teen years. 

This of course will affect their later ability to make decisions correctly, to control impulses and risk 

taking as adults. 

Another area of concern is that many adolescents may actually be using marijuana as self-medication for 

anxiety. This will increase their chances of long-term brain affects with chronic daily usage. 

We mentioned that adolescent brains can become more addicted than adults. A perfect example of this 

is nicotine addiction. We all know of adults that got hooked on cigarettes as teenagers, and how difficult 

it is for them to kick the habit if you will as adults, as opposed to, compared to people that get addicted 

as adults. The adolescent brain, because its reward systems are so much more active than the adult, and 

the fact that the synapses can be made stronger during the process of addiction, explains why nicotine 

exposure in adolescents causes much greater addiction than in the adult. 

An area of concern is the increasing use of e-cigarettes. While cigarette smoking may be declining in 

teenagers, the use of vape cigarettes and e-cigarettes is increasing. In fact, e-cigarettes contain four to 

six times more nicotine than regular cigarettes. This means that e-cigarettes may pose a greater threat 

for nicotine addiction in teen years than in the past with regular, conventional cigarettes. 

The part of the brain that controls addiction is more active in the teenager compared to the adult, and 

it's interesting that all kinds of addiction, not just addiction to drugs, but even video game addiction 

actually are using the same circuits. So, it starts to explain why teenagers can become so addicted to so 

many things, including electronic stimuli. 

With addiction, peer pressure is another factor that's pushing the adolescent brain to a greater level of 

vulnerability compared to the adult. The emotional parts of our brain are connected up before, several 

years before, our frontal lobes are fully connected. This explains many aspects of teen behavior. Their 

vulnerability to peer pressure, because they don't have their frontal lobe to say, "This is a bad idea." 

They're really going on risk and reward system. It also explains why they take more risks with or without 

peer pressure. It also explains why their decision making may not be at the level of an adult. We need 

our frontal lobes for organizational prioritization of lists and planning, and the teenage brain does not 

have full access to that part of the brain. 

The fact that the emotional parts of our brain connect up before our frontal lobes also explains why 

teenagers can be so emotional at times, and respond to things that we as adults may feel are 

inconsequential, as if they are international incidents. They really are experiencing emotion to a greater 

and higher, larger, extent than the adults. 
Dr. Jensen | Transcript Page 4 of 7

Functional imaging has shown that when we confront the adolescent with an alarming image, their brain 

areas that control emotion actually turn on higher and to a greater extent than children or adults. They 

really are experiencing emotion in techni-color as opposed to adults experiencing emotion in relative 

black and white. 

What we've learned about brain development helps us understand the bad reputation teens have for 

poor decision making, risk taking, and inability to consider the consequences of their behavior and think 

ahead. We now know that the teen’s brain is wired for learning. Teens can learn more quickly than the 

adult, which helps us explain why teenagers may be the only one in your house who knows how to fix 

the computer or smart-phone. 

The brain during the teenage years is also open to experiences that shape its development. This 

presents opportunities for parents, grand-parents, educators, and other adults to have a very positive 

impact on a teen’s life. Scientists increasingly view mental illnesses as developmental disorders of the 

brain, and that many of them have their roots in the process of brain maturation. By studying how the 

circuity of the brain develops, scientists hope to understand when and why brain development can 

result in mental illness. 

In fact, recent research is showing that many kinds of mental illness have their onset in late childhood, 

the teenage years, or early adulthood. This is not a coincidence. In fact, in order to be able to exhibit a 

mental illness, one has to have a certain level of brain development accomplished. An example of this 

would be schizophrenia, depression, bipolar disorder, which all need to have a certain level of 

functioning or dysfunction in the frontal and pre-frontal cortices. One thing we know is that adequate 

sleep is central to physical and emotional health. Research suggests that brain based changes in the 

regulation of sleep may contribute to a teens tendency to stay up late at night. 

Along with the obvious affects, such as fatigue and difficulty maintaining attention, inadequate sleep is a 

powerful contributor to irritability and depression. Studies of children and adolescents have also found 

that sleep deprivation can increase impulsive behavior. Mental illness affects one in four people at some 

point in their life span. In fact almost two thirds of people with major psychiatric conditions have their 

onset between 15 and 25. 

This means that the teen years and young adult years are a time of great vulnerability to the onset of 

these illnesses, and we should think about being extra vigilant for signs of mental illness at this window. 

This can be during high school or college, or a first job. These are typical times when someone might 

have their first symptoms of a mental illness. 

Understanding the changes taking place in the brain during this period presents an opportunity to 

intervene early in mental illnesses that often have their onset during the adolescent and young adult 

years. Research findings on the brain also serve to help adults understand the importance of creating an 

environment in which teens and young adults can explore and experiment while helping them avoid 

behavior that's destructive to themselves and others. 

So, what should all adults know about the new research that explains adolescent behavior? 

First, adolescents seem to take a long time to process an experience or make plans, or organize 

themselves, and sometimes it takes them a long time to consider the consequences of their behavior. 

Also, the teens perception of stress and anxiety is actually amplified compared to the adult. The onset of 

serious mental illnesses actually happens, typically, in late adolescence or early adulthood, as a function 

of brain development. 
Dr. Jensen | Transcript Page 5 of 7

It's important to know that the internet can actually amplify the consequences of teen behavior. Cyber 

bullying is an example, and this can increase the exposure to stressful stimuli of today's teens and young 

adults. 

Because teens’ brains can learn more quickly, teens are actually more prone to addiction than adults. 

But, on the other hand, they can learn faster. Given the new research about the teen and adolescent 

brain, these are things that all adults can do to support teens during this pivotal time of brain 

development. 

Be available for support and advice, and thinking through consequences of behavior. 

Provide a frontal lobe assist for your adolescent. 

Recognize that there is biology behind why teens tend to make more mistakes, so use these as 

teachable moments for your teenager. 

For instance, ask them, "Why do you think this happened?" And, "What could you do differently next 

time?" Work through the problems with them for a teachable moment. 

Stay connected and engaged in their lives. Show an interest in their activities, their friends, and their 

feelings. They need you more than they recognize. 

Sleep deprivation is not good for learning. Limit the use of electronics and other distractions at night 

while your teen is attempting to go to sleep. Learn how to use social media to stay connected to teens. 

Text, Twitter, Instagram, so that you can be part of their world. Share information about health and 

other risks without lecturing. 

I speak regularly to teens about brain development, and talk to them about minding their brain. I find 

that teenagers are naturally interested in their level of brain development. This is new information, and 

this is the first generation of teenagers that have had this much new information about where their 

brains are in development. Teens are at a point of trying to identify who they are, and this information 

can come in as a very important tool for a teenager as they are trying to explain their own behavior. 

Teens are excellent learners, and it is valuable to give them examples of cause and effect of some of the 

risks that they may be tempted to take, and their consequences. 

It's important to realize that mental illness often has its first manifestations in the teen or young adult 

age window, and so therefore we have to be a little extra vigilant about changes in our teenagers. I 

would say changes in their social behavior, if they're isolating themselves to an excessive amount, if 

they're dropping contacts with their friends, changes in their appetite, weight loss, weight gain, major 

changes in sleep, excessive irritability, are all signs of a possible problem in your adolescent. What we 

really mean is this is all on an individual basis. If you see a change occurring over weeks or months from 

what used to be your teenagers baseline to something different, that is a cause to stop and try to learn 

more, and if necessary contact your healthcare professional. 

There are some slight differences in brain development rates between girls and boys. In fact, on 

average, girls are approximately two years ahead of boys in the developmental trajectory. That means 

for a given age, girls will appear to be about two years ahead of boys on average. There are late girls and 

early boys, so it really is a very individual process. 
Dr. Jensen | Transcript Page 6 of 7

There are often big differences between girls and boys in early teen years or mid teen years with respect 

to the amount of organizational behavior they exhibit. Girls tend to be a little bit more organized and 

putting together planning to a greater extent than boys. This is likely because they're that much further 

along in development and in that frontal lobe connectivity. 

Similarly, studies show that males are often greater risk takers than girls, especially towards the end of 

the teen years. This may be explained by the fact that in general, male brains reach maturity later than 

female brain, and in late adolescence the frontal lobe of males may be less connected than females. As 

adults around teenagers, we may think about treating girls differently from boys, however actually it's a 

very individual process. I think we have to be mindful of where our teenager is with respect to their risktaking behavior or ability to plan, and again, where necessary give a frontal lobe assist. 

Teenagers are naturally novelty seeking. This is actually a consequence of their brain stage, in that their 

reward systems, their novelty seeking systems, are actually on high energy compared to later in life. At 

the same time, their frontal lobes are less connected than they will be later. This is of course one of the 

root causes of them taking risks, and sometimes those risks can be dangerous. However, there are good 

risks to take too, and we have to think about how we can take advantage of that natural novelty seeking 

behavior of a teenager to ask them to experiment with positive influences in their life. After all, we 

shape our brains through trial and error. Nature versus nurture. The environment shapes our brains. 

So, teenagers have an opportunity to even get more out of the environment than the adult for a given 

experience. We could imagine letting the teenager experience community service, or a summer job, or 

giving them new responsibilities at home, as well as of course all the opportunities that are available to 

them through their school. 

A really important message for adults, especially parents, is that teen behavior can be at times very 

frustrating to us as adults, and really provoke a sense of anger at times in adults. I would implore adults 

to use the new research on the teenage brain to actually be more patient with their children. Actually, 

behavior can be explained a lot by biology, and if you just step back and take that into account, it might 

help you to count to 10 and not alienate your teenager. 

They are going to need you for help with planning, assessing risk, and this is where we've often said an 

adult whose frontal lobe is healthily attached can give their teenager a frontal lobe assist. 

So, one thing that teenagers do have is an incredible ability to learn, and to learn lessons. As adults, we 

can use events that are happening around the teenager in their own life, or even events from your own 

personal history to explain to them the cause and effect, especially when it is around risk taking and 

dangerous risk taking and bad consequences. 

I think it's important that adults help the teenager understand where they are in development, and that 

they have sort of hidden strengths that they're not going to have again. One important message is that 

the brain is changing every day, every week, during this window of development, so what environment 

that the teenager is in during those days and weeks and years of adolescence, actually shapes their 

brain. It's a time of incredible scaffolding of the brain, and therefore I think we can explain to them that 

they have the ability to change their brain for better or worse, and of course we'd like the former not 

the latter. One message to teenagers is to use the research and the data that we have available to us 

from neuroscience to teach them these new facts. 
Dr. Jensen | Transcript Page 7 of 7

Teenagers are part of a data driven generation. We can use that to help them guide themselves, and 

recognize that his is a window of opportunity. I often say, "Mind your brain now, and it will mind you 

later." 

In this series we've pointed out several times that the teenage brain, the adolescent brain, has hidden 

strengths. One of those hidden strengths is their ability to learn. They have more synapses in their 

brains. We do our learning at our synapses, the connection between our brain cells, and they are able to 

grow more synapses and shape more synapses with experience than they will later in adulthood. 

Therefore it is a window of opportunity for them. 

Importantly, negative things can impact their ability to learn, which is a little ironic given the one thing 

they do really well is learn, and yet they put themselves in positions that might threaten their ability of 

the brain to learn. These include sleep deprivation, substance abuse, and stress. I think as adults we can 

inform teenagers of the effects of these negative influences on their brains ability to grow, develop, and 

to sustain that heightened ability to learn. 

Sleep is a really important factor in the brains ability to function normally. We consolidate our memories 

during sleep. Sleep deprivation impairs our ability to learn at any age, but of course teenagers, because 

they're learning so fast, are even more vulnerable to the effects of sleep. Interestingly, teenagers have a 

different sleep cycle than adults. I think many people think that teenagers are just lazy, they're not. It is 

because their sleep cycle is shifted. They release a hormone called melatonin at a later time than adults, 

and this brain chemical actually is what stimulates sleep and makes our brain want to go to sleep. We as 

adults put melatonin out at about 8:30, 9:00 at night, and about an hour and a half we feel sleepy. 

Teenagers on the other hand release melatonin more like 10:30, 11:00, so they aren't even ready to 

sleep until after midnight. In addition, they threaten their ability to sleep because they stimulate 

themselves with numerous electronic devices and light that will prevent their brain from going to sleep. 

As a result, teenagers can get sleep deprived very easily. Because their sleep cycle is shifted, we are 

waking them up at a time that their brain is naturally still wanting to sleep, so at 6:00 or 7:00 a.m. when 

the day starts for most of us, teenagers are basically in the same place as an adult would be at about 

3:00 a.m., because of this shift. Therefore, they may start the day in a somewhat sleep deprived state. 

We know a lot about the effects of sleep deprivation on the process of learning, and in fact sleep 

deprivation can prevent your synapses, those connection points, from actually becoming stronger 

during learning. Sleep deprivation can weaken that process. On the other hand, as I said before, sleep 

can actually strengthen learning that has already happened, so that if you fall asleep after you've 

learned something, you will actually consolidate that memory better. 

It really matters what the teenage brain is exposed to on a daily basis, and there can be long-term 

consequences of chronic exposure to negative things. Just like drugs and chronic use of drugs can affect 

later life brain function, chronic stress can actually affect the brain as well. It's been shown that chronic 

stress during adolescence can actually cause an increase in the risk of depression in adulthood. 

Of course, there's a lot of research that's very well established about the effects of stress and 

impoverished environments on children, but importantly, new research shows that this vulnerability 

extends to adolescence as well. That adolescence and young adulthood is also a time where stress can 

leave a long lasting mark on the brain.