'With new technology, we were able to develop the first study looking at how development of white matter relates to activities in the real world.' Berns suggests that doing adult-like activities requires sophisticated skills.

The study enrolled 91 adolescents aged 12 through 18 over a three-year period. DTI was used to measure corresponding structural changes in white matter.

Levels of involvement in risky behaviours were measured by a survey that included questions about the teens' thrill seeking behaviours, reckless behaviours, rebellious behaviours and antisocial behaviours.

'Society is a lot different now than it was 100 years ago when teens were expected to go to work and raise a family,' says Berns. 'Now, adolescents aren't expected to act like adults until they are in their twenties, when they have finished their education and found a career.'

The Centre for Disease Control (CDC) reports that 27,000 people aged between 10 and 24 die from bad decisions in the US alone every year, says an Emory release.

The study's findings were published in the Wednesday edition of PLoS ONE.