Research finds a screw loose in teenage brains

Adolescents have never been known for responsibility. And now science can tell us why. It’s all to do with the brain – and an important cog that just hasn’t learnt to work yet.

It is a world of slamming doors and crippling heartbreak. Suffocating awkwardness and acne combine with reckless rebellion to create a rollercoaster of emotions and experiences. For adults, it often seems that teenagers are from another planet. But why do adolescents act as they do?

A new piece of research may have brought us closer to an answer. Teenage brains, it seems, are lacking some of the essential cogs that control behaviour. The result is a machine that behaves in all sorts of strange and irrational ways.

For a long time, we have known that the mechanics of adolescent minds crank thoughts and feelings up a notch. New challenges and possibilities – not to mention hormones – make emotions go into overdrive. Some scientists now think that the brain’s reward circuits also go crazy, making teenagers hungry for new experiences and sensations.

But as these forces race ahead, another part of the brain is lagging behind. The prefrontal cortex is responsible for things like planning, analysis, organisation and impulse control. And while everything else is going haywire, it’s developing at a leisurely pace.

In other words, teenagers have a powerful accelerator – but no braking system.

It hasn’t always been like this. In the past, experts say, the prefrontal cortex – which grows in response to experience – was in sync with the rest of the mind. Childhood was spent preparing for adult life, cooking or caring for children, or learning an essential trade. Children would hit puberty at a later age than today, mentally prepared for a clear path of marriage, or a job for life.

When we hit adolescence today, however, life has been dominated by school and family. As we plunge into a tumult of hormones, independence and ambition, the part of the brain associated with responsibility is still developing. At the same time, the array of choices and challenges young people face has never been greater.

Teenage dream?

For many adults, the mismatch between teenagers’ abundance of desire and their lack of control is terrifying. A car with a powerful accelerator but no brakes, they say, would be far too dangerous for the road. Until teenagers are able to deal maturely with the modern world, they must be protected from it.

Recklessness may be risky, others argue, but it is what makes adolescence so creative and exciting. Yes, teens do make foolish decisions. But these are experiments in thinking independently and exploring what life is about. The unique mix of teenage passion and daring rarely comes again; before it fades into calm and acceptance, it should be seized and celebrated.

You Decide

  1. Is teenage recklessness always a bad thing?
  2. Is knowing about brain chemistry useful when it comes to understanding ourselves?


  1. Research into brain development can help explain why teenagers might feel drawn to certain types of behaviour, or fail to think things through. Try and think of a time when you have experienced this sort of situation, and create a piece of music, writing or art that explores your feelings about it.
  2. Teenagers haven’t always existed. The idea of teens first came about in the 1960s, when new freedoms led young people to create their own cultures. Research the history of the teenager, and create an infographic or short piece of writing to show how the phenomenon of teens came about.

Some People Say...

“Adults and teenagers can never understand each other.”

What do you think?

Q & A

What impact does all this have on what I can do?
Our knowledge about how teens think could have a big impact on public policy. Recently it has contributed to a UK debate about theage of criminal responsibility, which is currently just 10. When we are allowed to drive, marry or drink alcohol could be influenced by knowledge of brain development.
So does this research mean I’mnot responsible for my actions?
You won’t get off that easily. Many say knowledge of our brains actually gives us more opportunity to take control. We know, for example, that we can develop our prefrontal cortex by practising new skills, gradually exposing ourselves to controlled risks and learning from experience. If we know we can improve our mentality in this way, we’ve no excuse not to do so.

Word Watch

This comes from a Greek word hormon, meaning ‘to set in motion’. That’s exactly what hormones do: they’re powerful chemicals, secreted by parts of the body to send a message to other cells about how to behave. Hormones are absolutely essential in setting the changes of puberty in motion.
Prefrontal Cortex
The prefrontal cortex is the part of the brain that controls ‘executive functions’ – reasoning, decision making, planning ahead and analysing. It develops in response to learning and experience; as well as changing as we age, it changes as we study, as we take on challenges and as we make mistakes. It’s situated at the very front of the head.
Hit puberty at a later age
In the past, adolescence tended to happen to young people later, and today children are hitting puberty earlier than ever. Possible explanations for this vary, but it’s likely that having a heavier diet and less active lifestyle could be something to do with it.
Age of criminal responsibility
This is the age at which young people can be convicted of a crime. The age of 10 in England – and 12 in Scotland – is actually remarkably low compared to other developed countries. In Belgium, for example, the age is 18; in Spain, 16.

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