Frances Jensen

Neurologist and mother

"Teenagers are learning machines."

The brain is the body's most complex organ and the last to reach maturity

Teenage behavior, which can often seem irrational or reckless, may be rooted in problems related to how the brain develops, specifically the frontal lobe and the areas that control risk/reward centers. Before judging your children, you need to remember that sometimes their brains just aren't able to reach certain types of conclusions and that maybe it's your role to help them follow a particular line of reasoning. As a mother, I know that sometimes it's sometimes difficult to remain calm during an emotional outburst. However, if you stop to think about it, almost all behavior has a biological basis. It's worth remembering that teenage brains are more active than adult brains, as they have more cells and connections. Also, the frontal lobe of a teenage brain finds it more difficult to control certain emotions. Several studies have been performed using MRI scans which show that an adolescent's response to an emotional stimulus is double that of an adult.

For this reason, you should try to maintain a good relationship with your children, as they have very high stress levels and will therefore need your support, even during the first years of adulthood. It's up to parents to control their emotions and stop to think before judging.

It seems that it generally takes boys about two years longer to fully develop their brains than girls as regards synaptic pruning and the myelination required to isolate connections. However, all children are different, with some girls developing later and some boys developing earlier.

Are teenagers more susceptible to stress? The answer is yes, largely because they have a more intense unconscious response to emotional stimuli. Also, stress levels that could be temporary in adults might last longer for teenagers and may even result in post-traumatic stress disorders or depression years later. This is where synaptic plasticity comes into play. Synaptic plasticity is the way in which your synapses and connections are shaped depending on your experiences. For example, if a child studies music, they will develop more connections related to music. Synapses are also involved in the development of unwanted behavior such as a predisposition to experience addictions. This is because addictions are another way of learning that create stronger synapses in the reward circuits of adolescents than adults. Whenever I speak to teenagers I try to give them the following advice: "Take care of your brain now and it will take care of you in the future."

It's important to stress this point, as drugs have a greater effect on teenagers' brains as they are more vulnerable. For example, we know that alcohol consumption during the last years of adolescence affects the brain's synapses and changes its circuits. There are even studies that demonstrate that people who consume alcohol on a regular basis during their adolescence tend to take more risks when they're adults than those who don't. Similarly, the use of cannabis has been shown to decrease synapse activity, which impedes synaptic plasticity. In short, everything that happens to a person during their adolescence might permanently change the structure of their brain in the future.

A lack of sleep can also reduce a person's ability to create synaptic plasticity. Sleep deprivation should be viewed as another form of stress, and more so for adolescents, whose body clocks are different to those of adults. Adults start to secrete melatonin (the hormone that makes you sleepy) at around 9pm. However, adolescents don't start to secrete melatonin until around 11pm, which is why they find it difficult to go to bed or get up early, as it's the wrong type of sleep cycle for them. That's why many teenagers are chronically sleep-deprived, a fact that could make us stop and think whether we should take biology into account when planning school timetables.

Before ending this interview, I would like to invite teachers to check out the studies into the teenage brain that have recently started to be published, because, as educators, they're having an impact on the synaptic plasticity of their students. In my opinion, as well as stimulating their students and helping them to explore their feelings, teachers should also be aware of their emotional health. We now know a lot about how the brain works and can use all this information to help children have a happier adolescence and to encourage their brains to be more productive.

More on Frances Jensen

Frances Jensen is a leading authority on how teenage brains work. She is the Chair of the Department of Neurology at the University of Pennsylvania, taught neurology at Harvard Medical School for many years and is the Director of Translational Neuroscience and the Director of Epilepsy Research at Boston Children's Hospital. Ms. Jensen has written numerous books, including "The teenage brain. A neuroscientist's survival guide to raising adolescents and young adults", which explains how the brain functions during this intense period of growth.
How long does the brain take to reach adulthood? A person's brain won't be fully developed until they are 30, starting with the back and ending with the front. So, teenagers are only three quarters of the way closer to having a fully formed brain. Until relatively recently, we thought that brains stopped developing at around the age of 12. However, thanks to breakthroughs in magnetic resonance imaging and studies of cells and molecules, we now know that at this age, the brain still has a long way to go before it is fully developed. In fact, a person's IQ can change in adolescence as it is a very active stage in all senses. If you consider that human brains have around one hundred billion neurons and one hundred trillion synapses, which we lose as we age, you can conclude that children and teenagers learn more quickly and efficiently than adults. They really are like learning machines. However, they do have one disadvantage, which is that the frontal lobe is not fully connected to the back of their brains. We use the frontal lobe to process impulses, empathy, judgments, etc. As far as functionality is concerned, teenage brains have certain advantages and disadvantages when compared to adult brains. They also operate in a different way, which is sometimes difficult to comprehend.

"Teenagers are learning machines."

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