If a teenager blows your fuse,
check the wiring...

August 14, 2004   THEAGE.COM.AU

Research into the brain may help explain the maddening behaviour of adolescents. Jerome Burne reports.

Teenagers, parents endlessly moan, seem designed to infuriate any sane person condemned to live with them. Diva-scale sulks, rooms in which the floor is invisible, an inability to remember anything that involves anyone else, and a refusal to get out of bed until lunchtime are just a few familiar symptoms. And the anti-social behaviour is not limited to the home. Truanting children between the ages of 10 and 16 are said to be responsible for 40 per cent of street crime, 25 per cent of burglaries and 33 per cent of car thefts.

"When they shout, you want to shout the same thing back," says Kate Figes, journalist and author of The Terrible Teens, a book on raising teenagers. "When they are out having a good time with their friends and complain that home or family commitments are boring, parents easily feel rejected, unloved and misunderstood."

By and large, parents handle the outbursts of smaller children more effectively because they know they are children. Teenagers can be so infuriating and hurtful because both sides assume they are virtually adults. But what if much of classic teen behaviour is because their brains still aren't wired up properly?

"If we understand the way that the adolescent mind works, we stand a better chance of understanding why teenagers can be so sensitive and irrational," Figes says. "We are then less likely to overreact or blame them when they appear to be unreasonable or contradictory."

A report released in the US in May described how the brain matures in a gradual wave of development that travels from the back of the head to the front. The last bits to be fully wired up are the frontal lobes, the parts that decide to hold off sex tonight because you don't have a condom or finish your homework before going to the party. But the job is not completed until age 20 or later.

"One could speculate that some of the more immature aspects of adolescent behaviour may be due to the lack of maturity of some parts of the frontal lobes of their brains," says Judith Rapoport, lead scientist at the US National Institutes of Health in Maryland. This research is just the latest of a series of findings in the past few years showing that teenage brains are far more plastic than first thought.

When they shout,
you want to shout the same thing back.
KATE FIGES, journalist and mother

This can be seen as a great opportunity. "The research shows just how hopeless we are at giving teenagers what they really need," says Figes, whose novel What About Me? Diaries and e-mails of a Menopausal Mother to her Teenage Daughter has just been published.

"Just at the time when the finishing touches are being put to the control of their motor skills and they are at their most passionate and vulnerable, what do we do? We warehouse them all together in schools and cram them full of second-hand facts. Instead, they could be doing much more active learning, be much more involved with adults. We should also be much better at handling their need for risk and rites of passage."

So what exactly is this research that seems to have the potential to transform the stereotype of teenagers forever? For the past 13 years, Dr Jay Giedd has been peering into the brains of teenagers, using an MRI scanner at the National Institutes of Health. Taking neural snapshots every two years, he is building up a library of how the brain changes and grows.

"We started out trying to find out if there were brain markers for ADHD (attention deficit hyperactive disorder)," he says, "but we soon found we knew so little about how the brain developed normally that it was impossible to figure out where things might be going wrong." Before Giedd started his research the general view was that brain growth was finished by the age of 12. Some academics even claimed that adolescence was a cultural phenomenon that only emerged after the industrial revolution.

What has become clear, however, is that adolescents repeat a process that they went through in the period immediately before and after birth. Babies emerge from the womb with their brains only half-finished. Over the first three years, the brain continues to wire itself up at a furious pace, forming hundreds of thousands of new synapses a second. A two-year-old has more neural connections than an adult. Then between about three and five comes the purge. Circuits that are not used are ruthlessly excised. Giedd's remarkable discovery was that far from being finished at 12, the process of brain consolidation has an Act II.

Between the ages of six and 12, there is not much change in the number of neurons, but a big increase in the number of connections between neurons, which shows up as a thickening of grey matter on the scans.

Then as you enter adolescence the brain embarks on a second round of pruning, only this time it is the connections rather than brain cells that go - at the rate of about 0.7 per cent a year until the early 20s. At the same time there is a thickening of the white matter (the myelin sheath) that insulates the fibres linking nerve cells, speeding up transmission. "The result of all this," Giedd says, "is that you get fewer but faster connections in the brain."

The new "wiring" theory could help parents and others to become more understanding. "If you know all this is going on," Figes says, "it makes it easier to step back and not become quite so infuriated at the narcissistic, self-obsessed behaviour of your children.

"Our culture has a tendency to abandon teenagers, but actually the new picture of more hormones and less control means they need our support and love even more."

Suddenly, the inability of teenagers to get their homework done before settling into a long phone call seems more understandable. The executive functions that make those kinds of choices are not fully complete. The apparently wilful refusal to solve simple organisational problems - how to book cheaper train seats for a trip as well as getting clothes for the weekend party - doesn't look quite so hopeless either. One of the brain parts that does not completely connect till later is the corpus callosum, the bridge that links the two halves of the brain, which is involved in creativity and problem solving.

The tendency to ignore obvious risks, from smoking to unsafe sex, begins to make more sense, too. Sex hormones, seen as the usual culprits responsible for teenage bad behaviour in the past, still play a major role. But in the new model, while hormones provide the engine, the problems arise because the wiring for the control systems is still not in place. Take the feel-good brain chemical dopamine. The hormonal rush increases its levels and so feelings of pleasure become more intense. Without fully developed neuronal brakes, why put off the pleasures of sex, drugs or risk-taking?

Even the business of endless lazing in bed turns out to have a biological basis. One of the less appreciated effects of the rise in sex hormones is the effect it has on the rhythm of the sleep hormone melatonin. Teenagers go to bed and get up later because that is what their body clocks tell them to do. A society that requires them to turn up at school at 8am or 9am may be a recipe for mass teenage sleep deprivation.

These brain scans studies fit into a wider social picture, as shown in a review of scientific theories of teen behaviour conducted by researchers at Wisconsin University in 1987.

They found that in times of war and employment booms, scientists pronounced adolescents as being "capable and adult-like" but during peacetime and economic downturn, they characterised them as "psychologically incapacitated and slow to develop".

It is worth considering whether the simultaneous demonising and infantilising of adolescents tells us more about our society's need for good consumers than it does about the true nature of our children.

- The Independent