New guidance for psychologists will acknowledge that adolescence now effectively runs up until the age of 25 for the purposes of treating young people. So is this the new cut-off point for adulthood?
"The idea that suddenly at 18 you're an adult just doesn't quite ring true," says child psychologist Laverne Antrobus, who works at London's Tavistock Clinic.“
"My experience of young people is that they still need quite a considerable amount of support and help beyond that age."
"We are becoming much more aware and appreciating development beyond [the age of 18] and I think it's a really good initiative," says Antrobus, who believes we often rush through childhood, wanting our youngsters to achieve key milestones very quickly.
The new guidance is to help ensure that when young people reach the age of 18 they do not fall through the gaps in the health and education system. The change follows developments in our understanding of emotional maturity, hormonal development and particularly brain activity.
"Neuroscience has made these massive advances where we now don't think that things just stop at a certain age, that actually there's evidence of brain development well into early twenties and that actually the time at which things stop is much later than we first thought," says Antrobus.“
There are three stages of adolescence - early adolescence from 12-14 years, middle adolescence from 15-17 years and late adolescence from 18 years and over.
Neuroscience has shown that a young person's cognitive development continues into this later stage and that their emotional maturity, self-image and judgement will be affected until the prefrontal cortex of the brain has fully developed.
Alongside brain development, hormonal activity is also continuing well into the early twenties says Antrobus.
"A number of children and young people I encounter between the age of 16 and 18, the flurry of hormonal activity in them is so great that to imagine that's going to settle down by the time they get to 18 really is a misconception," says Antrobus.“
She says that some adolescents may want to stay longer with their families because they need more support during these formative years and that it is important for parents to realise that all young people do not develop at the same pace.
But is there any danger we could be breeding a nation of young people reluctant to leave adolescence behind? TV sitcoms are littered with such comic stereotypes of juvenile adults
Then there are those characters who want to break away from their overbearing or protective parents or guardians and reach adulthood, but struggle to cut the family ties.
Frank Furedi, professor of sociology at the University of Kent, says we have infantilized young people and this has led to a growing number of young men and women in their late 20s still living at home.
"Often it's claimed it's for economic reasons, but actually it's not really for that," says Furedi. "There is a loss of the aspiration for independence and striking out on your own. When I went to university it would have been a social death to have been seen with your parents, whereas now it's the norm.
"So you have this kind of cultural shift which basically means that adolescence extends into your late twenties and that can hamper you in all kinds of ways, and I think what psychology does is it inadvertently reinforces that kind of passivity and powerlessness and immaturity and normalises that."
Furedi says that this infantilised culture has intensified a sense of "passive dependence" which can lead to difficulties in conducting mature adult relationships. There's evidence of this culture even in our viewing preferences.
He does not agree that the modern world is far more difficult for young people to navigate.
"I think that what it is, is not that the world has become crueller, it's just that we hold our children back from a very early age. When they're 11, 12, 13 we don't let them out on their own. When they're 14, 15, we hover all over them and insulate them from real-life experience. We treat university students the way we used to treat school pupils, so I think it's that type of cumulative effect of infantilisation which is responsible for this."