Q: Is it true that during adolescence, the brain undergoes “extensive remodeling,” as one writer described it?
PVH: Yes. Our brain is developing all through our childhood years, going through very specific changes. But then at puberty, around age 12, it enters a second phase during which there are many changes specific to adolescence and beyond. In nearly everyone, this phase is complete around age 25. By then, the brain functions like an adult brain.
Q: What changes occur during adolescence?
PVH: The prefrontal lobes, a key area of the brain relating to will power, organization, concentration, mood, and the ability to get along with other people, decrease in size and become less efficient for a while. What happens is a bit like pruning rosebushes in February to prepare for a new burst of growth in the spring.
During adolescence, our brain goes through a similar pruning. It begins to get rid of whatever we no longer need now that we are heading into adulthood and a much higher level of neurological functioning. The neurological challenges we had to resolve as a child are behind us, and it’s time to move on to adult challenges. Thus, the brain shrinks down to prepare for the explosion in cellular growth and function needed to become a full adult brain.
Q: You said that the prefrontal lobes are less efficient for a while? How is this decreased efficiency expressed?
PVH: Impulse control can be more of a problem for teens than for some 10-year-old children. Teens sometimes find that their ability to do complex things, and to be organized and stay focused, gets worse for a while. A 12-year-old boy may be a great student, but at age 14, he may be struggling. These new deficits are often caused by the changes the brain is undergoing. This process can be as difficult for teens as for their families because their behavior may not be what the teens want, but they have difficulty controlling it.
Q: Why, all of a sudden, are the neurological changes of adolescence being discussed in the scientific literature?
PVH: Until recently, we had little understanding of the specific neurological changes that occur during adolescence because we didn’t have the right kind of imaging technology. With the new technology, we can actually see how the brain changes over time.
Q: Does this new understanding of adolescent brain development explain some of the aberrations in adolescent behavior?
PVH: Yes. People have long attributed these aberrations to raging hormones but the hormonal surge is a modest factor. The biggest factor is the revolutionary reorganization the brain undergoes during adolescence.
Q: Does our new knowledge explain why a love of thrill and openness to risk-taking are more common during the adolescent years?
PVH: Yes. A lot of risk-taking behavior is neurological. The brain is being reshaped in such a way that risk-taking or doing thrilling things releases dopamine, the risk-reward neurochemical, in the brain. We call it the “gambler’s neurochemistry.” People will engage in the risky activity of gambling in order to experience an incredible high when they’re successful. Even in anticipation of success at gambling there’s a surge in their brain’s dopamine levels, which we can see when we look at their brain chemistry.
These dopamine surges, which teens never experienced as younger children, “encourage” them to take more risks. As younger children they might have been very content playing with their action army figures or their dolls.
Q: Is adolescent brain development a linear process?
PVH: No. It is very up and down. That’s why in any given year, an adolescent might start behaving like an idiot even though he knows better. A year later, whatever triggered that behavior might no longer be a catalyst. Different things take on importance in different years.
Q: Will this new scientific knowledge enable society to view adolescence differently, and not as an aberrant period as is commonly assumed?
PVH: It should certainly help. What previously might have been viewed as aberrant behavior is often normal behavior for an adolescent.
Q: What is our obligation as adult members of society concerning the challenges adolescents face during this period?
PVH: First, we need to understand that the estimated end of this neurological adolescent phase is as late as age 25, which happens to be the age at which car rental companies will rent to young people. Second, there’s an escalating increase in the ways adolescents can do irreversible damage to their brains and nervous systems, and we need to know how to protect them from this danger. The use of marijuana and certain new technologies is very common in high schools. Both of these have negative effects on the developing adolescent brain.
Q: Taking these up one at a time: how are new technologies harmful to the developing adolescent brain?
PVH: Nowadays, it’s not unusual for teenage boys, by the time they enter their 20s, to have spent 10,000 hours playing video games on their computer. Malcolm Gladwell writes in his book, Outliers, that the brain needs to put 10,000 hours into an activity (such as learning a musical instrument) in order to master it neurologically. Many teenage boys are thus putting out a master level of energy and neurological patterning that is not helpful to their brains.
A study I read asks the question: “Is there such a thing as a technology addiction or internet addiction?” I think most physicians today would say: yes. Adolescents can become so dependent on the new technology that being deprived of it gives rise to the same level of agitation, anxiety, or depression that a smoker or cocaine user experiences when suddenly deprived of cigarettes or cocaine. When the technology is restored, their dopamine gets re-activated exactly as it would in a smoker or cocaine user.
So, yes, I think there is such a thing as internet or technology addiction. Controlling it comes down to families setting limits.
Q: Are any other problems caused by over-exposure to computer-related technology?
PVH: Yes. Nowadays many teenagers have mobile phones or tablets, and they sleep with them. They are thus exposed to wavelengths of light that have harmful effects on brain function and nervous system development.
Exposure to light during the night, especially of the blue light variety emitted by computer screens, smartphones, and tablets, prevents the release of melatonin, an important neurochemical hormone associated with sleep. A surprising number of teens will wake up two or three times a night and text their friends in the middle of the night.
The other risk for teens is that they are not getting enough sleep compared to 30-40 years ago when sleeping nine or more hours was not as difficult to do. Now it’s very difficult because of these electronic devices that they can use all night. Recent research shows that teens need to sleep at least nine or more hours to support their developing brains.
I’d also like to mention that addiction to the electronic devices can become socially isolating for teens at a time when it’s very important for them to be interacting with their peers. Suddenly they have the option of being totally self-satisfied, completely alone. They may even be happier in their chat room because there’s no social pressure, but that social pressure of human interaction is actually important!
Q: You mentioned that the use of drugs is also harmful to the adolescent brain?
PVH: Yes, as significant as technology addiction is, as a physician and neuroscientist, I’m much more concerned about the effects of marijuana and alcohol on the adolescent brain. There can be permanent harmful effects that persist throughout adulthood from even casual drug use.
Q: What kind of harmful effects?
PVH: They include lowered cognitive function, including memory and concentration; poor impulse control and anger management; and more of a tendency toward anxiety and depression. Even casual use seems to trigger these problems. Of course, the effects are much greater when adolescents use these substances regularly for years.
Q: Does occasional alcohol or marijuana use by mature adults produce similar effects?
PVH: The adolescent brain is affected differently by alcohol and marijuana than an adult brain. None of this is harmless, even to adults, but there aren’t as many permanent effects on cognitive function as are caused by even casual use in these younger years.
From the perspective of a neuroscientist, the number of negative changes that can occur to the adolescent brain from those two substances particularly is deeply disturbing. Of all illicit substances, those two are potentially the most dangerous, in part because they are widely available. I’ve been most disturbed by studies on marijuana use in adolescence. It’s surprising how even a very limited use of marijuana can harm the brain’s development in terms of memory and emotional control. Repeated exposure worsens the harm.
Q: At what age does this risk decrease?
PVH: At age 25, the brain has completely finished this critical period of development and is much more resilient to the neurological onslaught of something like alcohol or marijuana. Also risk-taking behavior has calmed down a bit, and there’s less chance of people using marijuana or alcohol to excess.
Q: Would teaching meditation to teens offset the tendency to use alcohol or marijuana?
PVH: Yes. Once children enter puberty, meditation can be very helpful with the kinds of challenges they face and either prevent or limit the kind of brain damage that can occur.
Q: How would meditation help?
PVH: Meditation would help curb risk-taking behaviors and improve their ability to control their emotions. Meditation would also have beneficial effects on the growth and development of their prefrontal lobes, benefits that would stay with them for the rest of their lives.
Q: Would you say, then, that meditation offsets some of the harmful effects of adolescent brain changes on prefrontal lobe functioning?
PVH: Yes, it does. Adolescence is also a time of increased socialization for adolescents, particularly with their peers. The prefrontal lobes are involved with one’s ability to interact harmoniously with other people. By learning to meditate, teens become better able to get along with other people in general, not only with their peers.
Peter Van Houten lives at Ananda Village and is the founder and Medical Director of Sierra Family Medical Clinic near Ananda Village. He frequently writes and lectures on the brain and other “yoga and science” topics.