Hilary Rose, 19 March 2019, the Times
Moody, lazy, selfish — secrets of the teenage brain explained
Why are the young prone to excessive risks and mental illness? We ask a top 1. /ˈnjʊərəʊsaɪəntɪst/ neuroscientist for answers
Teenagers tend to have a bad reputation for a good reason. One friend of mine was recently sworn at by his teenage son five times before 8 am. Another says that her household 2. /rɪˈvɜːbəreɪts/ reverberates to the sound of doors being slammed and regular reminders that everything she says and does is a cause of crippling embarrassment.
Enter the neuroscientist Sarah-Jayne Blakemore, who thinks teenagers aren’t difficult, just misunderstood. She has two adolescents of her own and has spent her career studying teenage brains. Adolescence, she says, isn’t an aberration and we shouldn’t 3. /ˈdiːmənaɪz/ demonize teenage behaviour. Embarrassment and moodiness are just normal stages of development.
“We’ve always put down the changes in their behaviour to them being difficult and lazy and selfish. Their 4. /ˈtɜːbjələnt/ turbulent moods and risk-taking, self-consciousness and rebelliousness,” she says. “But that really shows a lack of understanding of the developmental processes they’re going through, and probably for very good evolutionary reasons.”
Blakemore is professor in cognitive neuroscience at University College London, but when she was a student, 20 years ago, her text books said that human brains stop developing in childhood. That, we now know, is wrong. Thanks to developments in MRI scanning, scientists have shown that the human brain carries on changing and developing 5. /səbˈstænʃəli/ substantially through our teens and into our twenties and even thirties. Many scientific studies and the World Health Organisation define adolescence as the second decade of life. During this time the onset of puberty wreaks havoc on teenagers’ hormones and mood, their circadian rhythms change, affecting their sleep patterns, and, to cap it all, they are probably starting a new school with new friends. Their brains are preparing them for adulthood and independence, and if it makes them a bit stroppy we should cut them some slack, Blakemore argues.
“If adolescence is all about becoming independent, then it will involve taking risks and going out of the confines of the family home,” Blakemore says. “You have to forge social relationships and work out where you are in social 6. /ˈhaɪəraːkiz/ hierarchies. And adolescence involves developing a self-identity, particularly a social one. So the areas of the brain involved in social cognition, social understanding and peer influence are all undergoing huge amounts of change.”
This is the age when bullying can become more common, as a by-product of teenagers’ heightened desire to find their peer group and be accepted by it. “None of us likes to be socially excluded, but we know that adolescents’ feelings of self-worth and their mood and anxiety levels are affected even more than adults. There’s a lot of evidence that friends become particularly important in adolescence, more so than childhood or adulthood.”
And when they don’t go to bed till midnight, can’t get out of bed in the morning and sleep all day at the weekend, they are not being lazy, they can’t help it. “It’s normal before puberty for children to get up at 6am and be really energetic, and then suddenly, as teenagers, they can’t go to sleep until later than their parents,” Blakemore says. “It’s partly a natural shift in their biology. Teenage brains start producing melatonin, the hormone that induces sleep in humans, about two hours later in the evening. No one really knows why, but it happens in animals as well. Maybe in order to go off and become independent you need to be on a slightly different time zone from your family.”
By the time you’re eight, your brain is as big, physically, as it’s going to be. What happens inside is another matter. In adolescents, white matter increases, grey matter decreases and the speed with which synapses connect shoots up, making the brain quicker and more efficient. Environment is crucial. Babies are born with more synapses than they need, and those that aren’t being stimulated by their environment, for example in speech and social interaction, are discarded, while those that remain grow stronger, in a process called synaptic pruning.
“It effectively means that the brain is being shaped and moulded throughout development according to its environment. The brain isn’t fixed by a certain age, it’s shaped by the environment and what aspects are stimulating it.”
The 7. /ˈkɒnvɜːəs/ of that is that if a child is neglected — if his or her brain isn’t exposed to stimulation — then the damage to brain development can be, in Blakemore’s carefully chosen word, “detrimental”.
The teenage years are when a child starts the process of becoming an independent adult. There’s no average universal teenager behaviour, Blakemore points out, just as there’s no universal adult behaviour, but the tendency to take risks, be self-conscious and peer-influenced is generally higher in adolescence than at other ages. Where teenagers today differ from previous generations is in the rise in the number of mental health issues they are reporting, ranging from anxiety and depression to self-harm and eating disorders.
Blakemore thinks they are under more pressure than ever before, particularly over exams at school. Partly the rise is down to better reporting of problems, thanks to a reduction in the stigma attached to mental illness, but Blakemore’s colleagues in clinical psychology and child psychiatry are convinced that children are simply less happy than they were 20 or 30 years ago. So what’s changed? Social media?
“The evidence so far is not very strong that the problem is social media, phones, new technology, gaming. A very big study published recently, collating masses of data, showed almost zero effect of social media on wellbeing among British teenagers. Other things have changed too: school pressure, pressure about the future. They’re worried if there will be jobs for them and if they’ll ever get on the housing ladder. I’m not suggesting that phones are completely harmless, but social media 8. /igˈzæsəbeɪts/ problems, for example bullying, that sometimes are already there.”
The main 9. /ˈbʌgbeə/ bugbear Blakemore has with phones isn’t to do with social media per se, it’s teenagers taking them to bed with them. “The one thing we know is really important for development is getting a sufficient amount of good-quality sleep every night. Sleep is the thing we know is really important not just for brain development and learning, but for mental health.”
Blakemore was brought up in Oxford, one of three daughters. She read experimental psychology at St John’s College, Oxford, studied for a PhD at University College London, then did post-doctoral research on schizophrenia, much of it in France, in French, a language she didn’t speak well. She uses the experience to illustrate how adaptive even the adult brain is. The first six months of working in French were exhausting. After that, she found that her first thoughts were always in French, and it was translating back into English that she found tiring. She has forgotten most of it now because her brain has rewired itself to work in English, but if you knew something once, whether it’s a language or playing the piano, she says it should make it easier to learn it again.
It was her research into schizophrenia that got her interested in the adolescent brain because every one of the hundreds of patients she interviewed developed the symptoms between the ages of 18 and 26. What happened in some teenagers at this stage of development, she wondered, that made the brain go off course and develop schizophrenia? Very little was known about teenage brains at the time, so Blakemore set about finding out and helping the rest of us to understand it. She has written a book, Inventing Ourselves: The Secret Life of the Teenage Brain. In it she explores why many mental illnesses begin at this time, why teenagers develop intense friendships and can be prone to excessive risk-taking and why an easy child can become a difficult teenager.
“It’s a time when so many things are happening all at the same time: the huge increase in sex hormones at puberty affects mood and can induce surliness in teenagers. It’s very hard for them to have these massive 10. /ˌflʌktuˈeɪʃnz/ fluctuances in mood. And puberty makes them suddenly change physically. They go from being these cute little children to looking like an adult and they’re being treated differently by everyone because of that.”
Inventing Ourselves: The Secret Life of the Teenage Brain by Sarah-Jayne Blakemore is published in paperback by Black Swan on March 21, £8.99
