Janette Collins, a London-based youth counselor told the Financial Times last October. "It's the very few girls who score really well that you have to look out for."

"In my experience they're the ones who go off and get pregnant for real — you've accidentally taught them they can cope."

They drive at high speeds.

They stand around outside loud parties and smoke weed in front of the cops.

They guzzle liquor. They insult their parents - or lie to them - and feel no remorse, because, of course, their parents are idiots.

It is easy to blame peer pressure or wilfulness, but scientific studies suggest that at least some of this out-there behaviour has a physiological tie-in: brain mapping technologies show that the average teenager's brain looks slightly different from an adult's.

The biggest differences lie in the prefrontal cortex - a part of the brain associated with reasoning - and in the networks of brain cells that link the cortex to regions of the brain that are less about reasoning and thinking and more about emotion.

Using such tools as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), scientists have peered into teen brains and found that typically, until a person hits his early to mid-20s, his prefrontal cortex is still rapidly changing.

So are the cell endings and chemical connections that link the cortex to parts of the brain associated with gut impulses.

When people are around 15 or 16 years old, many brain cells in the cortex die off while others are created, and new connections form among them.

A lot of the basic cognitive abilities - advanced reasoning, abstract thinking, self-consciousness - rapidly expand during this time, says Laurence Steinberg, a Temple University psychology professor.

"The connections within the brain don't fully branch out until age 22 or so.

"The kinds of capabilities that connectivity contributes to - emotion regulation and impulse control - probably plateau in the early to mid-20s." Continue reading

Sources

• The Guardian
• Image: Stuff