The teenage brain
During the 1990s and early 21st century, research indicated that teenage brains are different to adult brains. By age 12 the brain is as large as it is at age 20. Research has shown that teenagers use different parts of their brains than adults when thinking about actions. Adults used parts of their brain that considered the consequences of actions on others, while teenagers were less likely to do this.
Teenagers can be susceptible to depression. They are less able to interpret social situations and other people’s emotions, and are also more likely to indulge in risky behaviours. In 2011 the driving age was raised from 15 to 16. Some lawmakers said that, if they had known what was now known about the teenage brain, the driving age would never have been set as low as 15.
A major survey of secondary school students in 2012 found that 90% reported that their health was excellent, very good or good and that they were feeling okay, satisfied or very happy with their life. Seventy-two per cent said they got on well with their families. However, many teenagers did take risks and have accidents. While road-safety campaigns, including those against drink-driving, have reduced death and injury rates among young men since the 1970s, the rates remain high relative to older adults. In 2014 one-quarter of road users killed or injured were aged 15–24, and 60% of these were male.
Flirting with delinquency
A landmark study of more than 1,000 people born in Dunedin in 1972–73 found that there were two main groups involved in anti-social behaviour such as minor crimes. One was a small group who remained offenders all their lives, while the second, larger group flirted with delinquency (vandalism or shoplifting) in their teens. They then ceased offending and settled down with jobs, families and friends.
Alcohol and drugs
Teenagers are great experimenters – for instance, many try smoking although most do not become life-long smokers. Most begin drinking alcohol in social situations in their early teens, even though they are legally not allowed to buy alcohol. One third of New Zealanders have their first drink at 14 or younger. The Sale of Liquor Act 1989 eased restrictions on alcohol sales, and in 1999 the drinking age dropped from 20 to 18. Many teenagers believed alcohol helped them relax, talk to people and get to know others.
Fifty-seven per cent of secondary students surveyed for the Youth '12 study had tried alcohol, 8% drank alcohol weekly or more frequently and 23% had engaged in binge drinking (five or more alcoholic drinks within four hours) in the four weeks before they completed the survery. Self-reported use of other drugs, such as party pills, was very low.
In the 1990s and early 21st century the consumption of ‘alcopops’ became popular with female teenagers. These ready-mixed drinks were cheap and easily available, and their sweet taste mimicked the soft drinks that many children were accustomed to. Boys typically began drinking beer in their mid-teens.
New Zealand has a binge-drinking culture which is not limited to the teenage years. In the 2000s teenagers were drinking more in a single session, and more at a younger age, than in the 1990s. As inexperienced drinkers with lower body weights and less tolerance for alcohol than adults, teenagers can get drunk much more easily. The major costs of this are drink driving, car accidents, property damage, violence and sexual assaults.
Binge drinking among teenagers declined in the early 21st century, suggesting messages about its dangers were having an effect. In 2001, 40% of teenagers surveyed had drunk to excess in the last four weeks, compared to 23% in 2012.
Experimentation with illegal drugs is common, but only a minority develop an addiction or a long-term habit.
Depression is an ongoing mood of severe unhappiness that continues for more than a couple of weeks. As depression can lead to suicide, and few young people seek help themselves, health professionals advise parents, relatives and friends to encourage depressed young people to go and see their doctor. One of the many risk factors for developing depression is being aged 16–24. Sixteen per cent of female secondary school students and 9% of male students reported symptoms of clinical depression when they completed the Youth '12 survey. Thirty-eight per cent of female students and 23% of male students reported 'feeling down or depressed' for at least two weeks in the preceding year.
Teenagers and brain growth
Taking around 18 years to mature is unheard of in other species. This is over 20% of a modern human’s lifespan and probably over half a hunter-gatherer’s life. Some scientists think that it was some time between 300,000 and 800,000 years ago that humans began reaching the age of 13 without being physically mature. The evolution of teenagers – humans aged over 12 who are not yet adults – may have preceded the massive growth of human brains that occurred around 250,000 years ago. This leads to the intriguing possibility that prolonged adolescence may have been one of the factors that contributed to increased brain size.
The World Health Organization defines ‘youths’ as those aged 15-24, and New Zealand has a high youth suicide rate compared to other OECD countries. However the teenage (15-19 years) male suicide rate has generally been lower than that for young adult (20-24 years) and middle aged males (35-49 years). Male youth suicide rates began to rise in the 1970s, peaked in the mid-1990s and declined from the late 1990s before rising again. While the female youth suicide rate is lower overall, it has steadily increased since the 1980s and in 2013 the highest rates among women were in the 15-19 age group. A higher male suicide rate does not mean that suicide is primarily a male problem. Females make more suicide attempts than males, but tend to choose methods that are less lethal.
The 2012 survey of secondary school students indicated that 21% of the female students and 10% of the male students had thought about suicide in the previous year. Two per cent of the male students surveyed reporting attempting suicide during that time.