When my son turned 13 and started doing things that made me say WTF more than a few times, a friend recommended I read The Teenage Brain.
“Trust me,” she said. “It’ll explain everything.”
The Teenage Brain: A Neuroscientist’s Survival Guide to Raising Asolescents and Young Adults is written by Dr. Frances E. Jensen, a neurologist and mom of two teenage boys.
It’s a slim paperback explaining the brain science behind common teenage behavior from risk taking, alcohol and drug use to online addictions, concussions, and mental illness.
It is a bit dense at times so if diagrams of the anatomy of neurons are not your thing, here are my key takeaways.
The teenage brain is like “a puzzle awaiting completion.”
At birth, the human brain is only 40 per cent complete. It grows not only in size as our kids grow, but also in function. All the internal wiring changes.
This wiring begins at the back of the brain in the cerebellum (for balance and coordination), the thalamus (for sensory signals such as hearing, sight, smell, touch) and the hypothalamus (for bodily functions such as hunger, thirst, sex and aggression).
The frontal lobe–home to judgement, insight, and the ability to assess risk to onesself–is the last to be connected. The net result: teens have a habit of finding themselves in dangerous situations without knowing what to do next.
The teenage brain has an overabundance of grey matter and an under-supply of white matter.
Grey matter contains neurons, which respond to stimuli from the world. This is where all the action takes place. The axons, the wiring that connects grey matter in one part of the brain to another, are called white matter.
As signals travel repeatedly along the same axons, myelin, which has a white colour on brain scans, develops. The myelin insulates the connection allowing information to travel faster through the brain. Kind of like a subway tunnel through a city.
The tunnels to the frontal lobes are not fully insulated until kids are in their early twenties, so beware!
All those excitable neurons in the grey matter want your teenager to seek out new information and experiences–things they’ve never tried before. But, because information travels slowly to the frontal cortex, judgement and foresight are slow to put the brakes on dumb ideas.
Hormones are an issue for teenage brains, but we can’t blame them for everything
In fact, teenagers have no more hormones than adults, but they are a bit like toddlers when it comes to their sex hormones. Teens are seeing these hormones for the first time and, like toddlers, they haven’t yet learned how to react to them in an adult manner.
With puberty, the concentration of sex hormones changes dramatically. In girls, estrogen and progesterone, which fluctuate with the menstrual cycle, are linked to chemicals in the brain that control mood.
In boys, blame testosterone, which likes to hang out with the amygdala, the structure of the brain that controls the flight or fight response.
Why does this matter? All sex hormones are particularly active in the limbic system, which is the emotional centre of the brain. It makes teens emotionally volatile AND it makes them seek out emotionally charged experiences.
Teenagers react differently than adults to stress.
So, we have emotionally volatile teens with some faulty wiring, who crave emotionally charged experiences. The net result is often stress. But guess what? Teenagers react differently than adults to stress.
The hormone tetrahydropregnanolone (THP), which is released in response to stress, is at the root of the problem. In adults, THP quiets the neural system within 30 minutes of an anxiety event. It does the opposite in teenagers. It excites the teenage brain, increasing anxiety and panic.
THP is created when progesterone is metabolized. Boys also have progesterone, but in much smaller amounts than girls. This may explain why teenage girls are more likely to develop anxiety disorders.
Teens are biologically programmed to stay up late
The reason for the shift is melatonin, a hormone that induces sleep. During the teenage years, melatonin is released two hours later in teens than in adults. It also stays in their system longer in the morning, making it harder for them to wake up.
Coupled with early start times for school and sports, teenagers wind up chronically sleep deprived. While scientists recommend 8 to 10 hours of sleep every night for teens. the average teenager gets about 7 hours. This is bad because the teenage brain sheds grey matter–the excitable neurons– while sleeping.
While teens sleep, their brains are storing important information for later use pre-frontal cortex. They are also clearing useless information from the hippocampus, to make room for tomorrow’s flood of stimuli.
This nightly housekeeping is critical for our overall health, including mental health, learning, and memory, as well as our metabolism, immune system, cardiovascular system and more.
Dopamine is ruling the roost
“The chief predictor of adolescent behaviour, studies show, is not the perception of risk, but the anticipation of the reward despite the risk,” Jensen writes.
There are two areas of the brain responsible for this reward-seeking behaviour: the nucleus accumbens and the ventral tegmental area (VTA). When they are activated, they release dopamine, which feels good — it boosts our mood and increases our motivation.
Both of these structures are not only more active in the teenage brain, they are controlled by the frontal lobe, which, we know, is not fully connected. Scary, right?
As a result, teenagers are at risk of more easily developing addictions to things such as drugs, alcohol, vaping, online gambling, social media, and less likely to be able to control their desire for these things or learn from their mistakes. Social media and Fortnite obesessions are beginning to make sense.
What you can do as a parent to help navigate the scary years
If you’re feeling even more terrified of the teenage years, here are a few tips for parents from Jensen:
Tell your child every unfortunate or tragic story you hear about teenagers who made bad decisions and paid the price. Remind them that bad things can happen very easily over and over again because they have trouble remembering these things.
Encourage a good night sleep by reducing exposure to blue light before bed. You may not be able to control when their school starts, but maybe you can insist on no phones in bedrooms after a certain time. Sleep affects so many other aspects of teenage (and adult) life, including academic performance, athletic performance, brain development, mental health, skin, hair, weight, diet, motivation. I figure if we can get that right, it will may make everything else easier.
Finally, have a low threshold when it comes to seeking medical advice or support. Teenage brains are exceptionally vulnerable to stress, addiction and mental illness. They also have a poor ability to assess situations. All this to say, if you see concerning behaviour, be concerned.