Secrets of the teenage brain

Why are teenagers such moody, lazy, selfish nightmares? We gave readers the chance to ask Frances E Jensen, author of a new book on the adolescent mind, how to deal with these hormonal time bombs

Teenage brains
What’s going on in there?: ‘Very smart adolescents will do very stupid things in a very impulsive way,’ says Frances E Jensen. Photograph: Scott Camazine/Alamy

Several years ago Frances E Jensen’s 16-year-old son wrote off a car. A few years earlier, her other son had returned from a friend’s house with his hair dyed jet black. The University of Pennsylvania neurologist was finding her teenagers’ erratic behaviour increasingly taxing, so she decided to study teenage thought processes and gathered her research in the book The Teenage Brain. She found that while much had been written about teen psychology and parenting, no one had explained the neurons and cerebral connections that make those years such a unique – and terrifying – part of growing up. The teenage brain has only recently become a subject for serious research, which shows how little was known about it.

But does knowing what is going on in a teenager’s brain make them any easier to live with? Without a doubt, says Jensen, who thinks that her research allowed her to be more patient with her sons. “We expect a little bit more out of adolescents than we should, given where their brains are,” she says.

Given that the relationship between parents and teenagers is one of the most fraught in family life, we asked readers to send in questions for Jensen to tackle.

Clothes left in the bathroom, losing things, plates festering under the bed… Why doesn’t my teenager care about being tidy? Tidiness needs a sophisticated level of cognitive control, and the way the teenage brain is connected means that their planning is not very good. Parts of the brain connect to each other through synapses, which are insulated, just like electric wires. That insulation is a fatty substance called myelin, which is created over time. The process takes years, and it starts at the back of the brain and slowly moves forward. The last bits of the brain to connect are the frontal and prefrontal cortices, where insight, empathy and risk taking are controlled. This means that very smart adolescents will do very stupid things in a very impulsive way. I don’t think organisation is a high priority for most teenagers. They have other things to worry about – they are messy because they don’t give themselves enough time to tidy up before they run off to do something else.

No-go zone: the teen bedroom should be entered with caution.
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No-go zone: the teen bedroom should be entered with caution.

Why does my daughter always seem so angry, especially with me? Teenagers can get frustrated with situations and themselves, as a lot of things still aren’t fitting together in their brain. The risk-taking behaviour and impulsivity they exhibit because they don’t have full access to their frontal lobes can cause mood swings and fuel conflict and anger. Adults can respond to this behaviour in an angry fashion themselves. While I’m not condoning teens’ erratic behaviour, the hope is that by understanding what is going on inside their child’s head, parents will be a bit more patient and might be able to stop themselves reacting and setting up a vicious cycle by alienating their child. Try to stay close to your teenagers, even if they seem to push you away. Always count to 10 and think twice. This is a time when mental illness can come on, and anger can be a front for depression or other anxiety disorders. Are they just being surly, or is there another explanation?

I feel increasingly cut out from my teenager’s life. Why won’t they talk to me properly? The teens are an age of self-discovery and novelty-seeking behaviour, and it’s natural that they will start to cut ties. Teenagers need to become independent, but we live in a very complex world, and no other teenage generation in history has had this much stimulation and exposure to the many potential stresses that arise from their being online. Because of this, parents do need to be vigilant and stay connected with them. I used to love car drives with my children because we were just looking straight ahead, and the lack of eye contact helped us to start talking about sensitive things.

Why won’t my teenager go to bed, and why can’t I get them up in the morning? There is absolutely a biological basis for this. In many other mammals, like baby rodents, sleep patterns shift during the adolescent period. From puberty to the end of the teens, the circadian clock is actually programming them to go to sleep and wake up around three to four hours later than adults. This is a problem, as they are relatively sleep deprived when you wake them up at 8am. It’s something we might want to think about as a society and in education systems, as chronic sleep deprivation is certainly not helping teenagers do their biggest job, which is to go to school. We know how important sleep is for consolidation of memory and learning. It’s all about strengthening synapses, a process which is chemically impaired in a sleep-deprived brain. This could be a reason for the fights, too – everyone knows that sleep deprivation makes you emotionally impulsive.

‘We expect more out of adolescents than we should,’ says Frances E Jensen.
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‘We expect more out of adolescents than we should,’ says Frances E Jensen.

Given the way the teenage brain works, should we lower the voting age to 16? I think that society on both sides of the Atlantic and in most parts of the world is hugely confused, with dozens of mixed messages for teenagers. One example of this ambivalence is that in the US we send 18-year-olds to war yet we don’t let them drink. From what I’ve learned, the data would suggest that if you’re looking for a vote to come from somebody who you trust to make rational decisions using cause and effect, and some insight, the average 16-year-old will not yet be at that point. Also, as teens are so impressionable, the concern is that their opinion might be overly swayed by others and override their decision-making.

My teenager doesn’t seem to care about school at all. Why are they so uninterested in doing their homework, and how can I motivate them to study? How many other competing interests do they have? For many teenagers, it’s certainly more fun to play a video game or go on Facebook than do their homework. It’s an issue we all face in the modern world, but serious demotivation can be a symptom of learning or processing problems. In that case, the teenage years are an ideal time to diagnose any problems and help work on their strengths as well as weaknesses. People have different learning styles, and there is a lot of opportunity for plasticity before your brain is fully mature. Teenage brains have more synaptic connections than adult ones, which makes them highly impressionable, as they’re building synapses and modifying them as they learn. They are primed to learn quickly and can memorise things faster. People might think their capacity for academic achievement is set in stone from a very young age, but this can change quite dramatically over adolescence. It’s a period of huge opportunity, and this suggests that you can really change your destiny with respect to how you function at school if you get some attention during this time.

Should I worry about my teenager drinking or dabbling with drugs? The same quantity of drugs or alcohol has a much stronger effect than it does in adults. Binge drinking can cause brain damage in teenagers where it will only cause intoxication in adults. We know hard drugs can also do more damage to young brains for the same dose. Teens are primed to learn quickly – but addiction is actually a form of learning, and they get addicted faster than they would if they were exposed to the same substances later. Chronic pot smoking has a long-term effect, as it’s actually changing your brain chemistry, just like enriching environments and academic learning do. Studies show that if you smoke pot on a daily basis for prolonged periods of time in your teen years, your verbal IQ drops.

Addiction is a form of learning, and teens get addicted faster than they would later in life.
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Addiction is a form of learning, and teens get addicted faster than they would later in life.

Why can’t my teenage children leave their smartphones alone, even at the dinner table – surely Instagram can’t be that interesting? The teenage brain is hungry for stimulation. But there is an unprecedented amount of it in today’s world, maybe more than ever. Because teenagers lack access to their frontal lobes, using their judgement to say: “I’ve had enough” or “I need to stop and do something else” is still a weakness for them. Studies have shown that while teenagers are better at learning to multitask than adults, distraction from smartphones and other devices can still impair learning, so they should switch them off completely when they’re trying to study.

Why don’t teenagers wear coats, even in very cold or wet weather? I don’t think there’s a biological basis for this. It could be an example of their lack of executive function along with their risky, impulsive behaviour – they’re not planning ahead. Their priorities are not as common sense as they will become over time. Also, teenagers will do outlandish things to please their peers, even if it means getting wet.

My child loves playing video games. What effect do they have on the teenage brain? Video games are another source of stimulation that teen brains respond exuberantly to. But as their brains respond more strongly to stress than adult brains, they have to learn to put what they see and do in the games into perspective. Adults must remember that as our frontal lobes are connected, we can reflect and do things in moderation. If teens overfocus on video games to the extent they’re not interacting with real people, that’s a problem. Video gaming and gambling use the same reward circuits as getting addicted to a substance.

How can I look after my teenager’s mental health? You need to stay connected with your teenager. Consistent social problems can mean that there may be an anxiety disorder or another psychiatric problem, such as depression, that’s beginning to emerge. Bipolar disorder and schizophrenia often come on at the end of teenage years and in the early 20s, because you need your frontal lobes to manifest those disorders. That’s why when kids seem to be socially isolated or gain or lose a lot of weight or stop taking care of themselves, parents need to be aware of it, as this might be the first sign of a deeper problem. Ironically, at this age if they do have an emerging mental illness, not all of their peers are as well equipped to be understanding as adults would be, because they don’t have the empathy skills.

The Teenage Brain by Frances E Jensen is out now (HarperCollins, £12.99). To buy it for £9.99, go to bookshop.theguardian.com or call 0330 333 6846