Today’s adolescents are the first generation to have grown up less healthy than their parents, doctors said yesterday.

Alcohol, tobacco, drugs, obesity and sexually transmitted diseases have replaced childhood infections of the past, such as tuberculosis and polio, and are exacting a greater toll. The difference is that the modern threats to teenagers’ health are preventable.

Between 1970 and 2000, obesity in adolescents has increased fourfold; sexually transmitted diseases have increased threefold; teenage pregnancy rates in Britain are the highest in Europe (despite a recent fall); drinking has increased; smoking rates are unchanged since 1982; and suicide is slightly up in the 30-year period (despite a recent decrease), figures show. The trends are highlighted in a series of papers on adolescent health published by The Lancet today, which the journal says is an area of medicine that remains “neglected, marginalised or ignored”.

Adolescence is the time when teenagers start smoking, drinking and having sex - behaviour which could have a huge impact on their long-term health, the journal said. But, it added, the opportunity to intervene was being missed.

Speaking at the launch of the series in London yesterday, Russell Viner, a specialist in adolescent health at University College Hospital, said the ages at which young people were permitted to vote, drink, drive or buy cigarettes were out of kilter with their biological and social maturity.

“Young people are the only group in the population where every health indicator is either static or adverse. We have less old fashioned infectious disease, but it has been replaced by social causes of death and illness which are causing significant health problems that weren’t there 40 years ago,” Dr Viner said.

“[Teenagers] in the second decade of life outnumber [children] in the first decade, but 95 per cent of the resources [for health] are focused on children. This group has been absent from the public health challenge.”

Many young people remained tied to their families until well into their twenties, despite having become biologically mature in their early teens. The modern mismatch between biological maturity and social maturity, marked by marriage or financial independence, had coincided with an increase in risky behaviour leading to injuries, mental disorders and suicides.

Dr Viner said: “There is a very large gap after puberty when young people don’t have the institutions of adulthood to control those behaviours until they are into their twenties.

“We need to rethink all the age limits. The age 18 is graven in stone, but there is little biological validity for it. Young people should be able to vote at 16 - the majority have well developed abstract thinking. But maybe some age limits should go up.”

Glenn Bowes, a professor of paediatrics at the University of Melbourne, Australia, said adolescents were at particular risk from the drinks industry. “High-potency products are being heavily marketed to get young people to drink before the legal age, which is having a very negative impact but is all denied by the industry. Let us hope it does not take us decades to recognise the impact it is having, as it did with tobacco,” he said.

Professor Andre Tylee, of the Institute of Psychiatry at King’s College London, said mental disorders were increasing, but that there was little guidance on how to engage young people in treatment.

Teenage risks

* OBESITY

Proportion of adolescents defined as obese quadrupled from 4-5 per cent in 1972, to 21-23 per cent in 2002.

* SEXUALLY TRANSMITTED DISEASE

Rates of chlamydia infection among 16 to 19-year- old women doubled during the 1990s and has continued to increase.

* SMOKING

No significant change in regular smoking among 11- to 15-year-olds since 1982, while smoking among adults declined significantly during late 1980s and early 1990s.

* DRINKING

Average amount of alcohol drunk by 11- to 15-year-olds doubled from 0.8 units a week in 1990 to 1.6 in 1998. In 2002, 18 per cent of 11 to 15-year-olds drank at least once a week.

* TEENAGE PREGNANCY

Births to 15- to 19-year-olds have changed little since the late 1970s, while rates have fallen markedly across Europe.

* SUICIDE

Increased in 15- to 24-year-olds until late 1990s.