Teenagers binge drink, take drugs and have unsafe sex because they are programmed to take risks, new research shows.
They are more likely than other age groups to indulge in dangerous behaviours – particularly after enjoying the buzz of a "lucky escape", say scientists.
A study of 86 boys and men aged nine to 35 who played computer gambling games found teenagers most enjoyed the thrill of a risky situation – with 14 year-olds the biggest culprits.
Unlike children they were also good at weighing up the pros and cons of their actions – it was just they found taking a chance more fun than playing safe.
Dr Stephanie Burnett, a neuroscientist at University College London (UCL), said: "The reason teenagers take risks is not a problem with foreseeing the consequences.
"It was more because they chose to take those risks.
"This is the first evidence from a lab-based study that adolescents are risk-takers. We are one step forward in determining why teenagers engage in extremely risky behaviours such as drug use and unsafe sex."
The study participants were asked to play computer games during which they made decisions in order to win points. After each one scientists measured their emotional response by recording how satisfied or dissatisfied they were with the outcome.
They found the onset of the teenage years marked an increase in how much enjoyment resulted from winning in a "lucky escape" situation.
The researchers whose findings are published in Cognitive Development said this could help explain why teenagers are more likely to take bigger risks.
Dr Burnett said: "In the game our participants were given a small chance of winning a lot of money or a safer option of winning a small amount of money.
"We found that teenagers much preferred the riskier spin of the wheel even though they were well aware of the consequences.
"In adolescence our brains are still developing – particularly the dopamine system which helps us feel pleasure and reward.
"Teenagers love screaming themselves hoarse on thrill rides at theme parks and this is a first step towards understanding why.
"It could be that we need to look at educating youngsters in a slightly different way about the dangers of drinking, taking drugs and indulging in other harmful activities.
"Telling them something is risky has always had the capacity to backfire by encouraging them to do something they shouldn’t. And now we know why."
Males are regarded as the more risk-taking sex but Dr Burnett now plans to carry out a similar study in females to see if the results are the same.
The co researcher Dr Sarah-Jayne Blakemore, also a neuroscientist at UCL, said: "The onset of adolescence marks an explosion in ‘risky’ activities – from dangerous driving, unsafe sex and experimentation with alcohol, to poor dietary habits and physical inactivity.
"This contributes to the so-called ‘health paradox’ of adolescence, whereby a peak in lifetime physical health is paradoxically accompanied by high mortality and morbidity.
"Understanding why adolescents take such risks is important for public health interventions and for families." (Daily Telegraph)