Adolescence now lasts from the ages of 10 to 24, although it used to be thought to end at 19, scientists write in The Lancet. Young people continuing their education for longer, as well as delayed marriage and parenthood, has pushed back popular perceptions of when adulthood begins.
Changing the definition is vital to ensure laws stay appropriate, they write in an opinion piece. But another expert warns doing so risks "further infantilising young people", the report says.
Puberty is considered to start when the part of the brain known as the hypothalamus starts releasing a hormone that activates the body's pituitary and gonadal glands. This used to happen around the age of 14 but has dropped with improved health and nutrition in much of the developed world to around the age of 10.
The report says as a consequence, in industrialised countries such as the UK the average age for a girl's first menstruation has dropped by four years in the past 150 years. Half of all females now have their period by 12 or 13 years of age.
There are also biological arguments for why the definition of adolescence should be extended, including that the body continues to develop. For example, the brain continues to mature beyond the age of 20, working faster and more efficiently. And many people's wisdom teeth don't come through until the age of 25.
The report says young people are also getting married and having children later. Lead author Professor Susan Sawyer, director of the centre for adolescent health at the Royal Children's Hospital in Melbourne, writes: "Although many adult legal privileges start at age 18 years, the adoption of adult roles and responsibilities generally occurs later." She says delayed partnering, parenting and economic independence means the "semi-dependency" that characterises adolescence has expanded.
This social change, she says, needs to inform policy, such as by extending youth support services until the age of 25. "Age definitions are always arbitrary", she writes, but "our current definition of adolescence is overly restricted. The ages of 10-24 years are a better fit with the development of adolescents nowadays."
Professor Russell Viner, president-elect of the Royal College of Paediatrics & Child Health, said: "In the UK, the average age for leaving home is now around 25 years for both men and women." According to the report, he supports extending the definition to cover adolescence up until the age of 24 and says a number of UK services already take this into account. He said: "Statutory provision in England in terms of social care for care leavers and children with special educational needs now goes up to 24 years," as does provision of services for people with cystic fibrosis.
'Infantilising young people'
But, the report says, Dr Jan Macvarish, a parenting sociologist at the University of Kent, says there is a danger in extending our concept of adolescence. "Older children and young people are shaped far more significantly by society's expectations of them than by their intrinsic biological growth," she said. "There is nothing inevitably infantilising about spending your early 20s in higher education or experimenting in the world of work."
And we should not risk "pathologising their desire for independence". "Society should maintain the highest possible expectations of the next generation," Macvarish said.
The report says Viner disagrees with Macvarish's criticism and says broadening adolescence can be seen as "empowering young people by recognising their differences". "As long as we do this from a position of recognising young people's strengths and the potential of their development, rather than being focused on the problems of the adolescent period."
Adolescence is the phase of life stretching between childhood and adulthood, and its definition has long posed a conundrum. Adolescence encompasses elements of biological growth and major social role transitions, both of which have changed in the past century. Earlier puberty has accelerated the onset of adolescence in nearly all populations, while understanding of continued growth has lifted its endpoint age well into the 20s. In parallel, delayed timing of role transitions, including completion of education, marriage, and parenthood, continue to shift popular perceptions of when adulthood begins. Arguably, the transition period from childhood to adulthood now occupies a greater portion of the life course than ever before at a time when unprecedented social forces, including marketing and digital media, are affecting health and wellbeing across these years. An expanded and more inclusive definition of adolescence is essential for developmentally appropriate framing of laws, social policies, and service systems. Rather than age 10–19 years, a definition of 10–24 years corresponds more closely to adolescent growth and popular understandings of this life phase and would facilitate extended investments across a broader range of settings.
Susan M Sawyer, Peter S Azzopardi, Dakshitha Wickremarathne, George C Patton
[link url="http://www.bbc.com/news/health-42732442"]BBC News report[/link]
[link url="http://www.thelancet.com/journals/lanchi/article/PIIS2352-4642(18)30022-1/fulltext"]Lancet Child & Adolescent Health abstract[/link]