Arecent issue of news magazine Time has on its cover a map
of a teenage brain and the statement: “Research is revolutionizing
our view of the adolescent mind – and explaining its mystifying
Parents who have teenagers whose only communication is a shrug and
the word “whatever” will discover, if they read the accompanying
report, that it isn’t just hormones which rule behaviour but also
structural changes in the brain that occur in adolescence.
Jay Giedd, chief of brain imaging at the National Institute of
Mental Health in Maryland, has been tracking the development of the
teenage brain for 13 years. Until recently, most scientists
believed that the brain was largely a finished product by the time
a child reached the age of 12.
Now, with the help of magnetic resonance imaging, which involves no
radiation, a different pattern has emerged. The most intensive
period of growth for the brain is in the womb. Just prior to birth,
extensive pruning removes brain cells that are under-used, and
research is beginning to suggest that autism results if the process
goes awry. What Giedd has discovered is that, in addition to this
prenatal growth, there are two more waves of proliferation and
pruning in late childhood and the teen years.
In teenagers, the last part of the brain to grow is the section
responsible for the executive function. This sets priorities, plans
ahead, suppresses impulses and weighs up consequences. It can’t be
long before defence lawyers are arguing that their clients’
misdemeanours are the result of a poorly developed prefrontal
Since scientists estimate that a brain probably doesn’t reach full
maturity until the age of 25, it makes it seem even more absurd
that in the UK we consider children fully culpable and place them
in the dock. In the US, of course, it’s even worse. Over there,
teenagers are executed.
According to Giedd’s research, the still developing brain
continually responds to redirection, given the right kind of
investment of stimulus and care. “You can tell them to shape up or
ship out,” he says, referring to adolescents. “But making mistakes
is part of how the brain optimally grows.”
In the mushrooming industry of parenting courses, perhaps it’s time
to introduce a down-to-earth guide to neuroscience – not least
because it might convince a doubting parent that it’s never too
late. They really can help a teenager to think again.