Young people * Mental wellbeing

IQ "not fixed" in teenagers

IQ  not fixed  in teenagers Brain scans provide clues

A person's intelligence quotient is supposed to be a general measure of their brain power and is assumed to be stable across the years.

But new research by scientists at University College London and the Centre for Educational Neuroscience has found that someone's IQ can rise or fall during the teenage years, and that these changes are linked to changes in the brain's structure.

These findings are important as the assumed stable nature of the IQ means that it is often measured only one or twice in a person's lifetime, but is then used to predict educational achievement and employment prospects later in life.

The researchers, led by Professor Cathy Price, tested over thirty healthy adolescents in 2004 when they were aged between 12 and 16. The tests were then repeated four years later with the same teenagers, now aged between 15 and 20. On each occasion brains scans of the subjects were taken using magnetic resonance imaging (MRI).

Significant changes in the IQ scores were found between the two sets of test. Some teenagers' IQ's improved by as much as 20 points compared to people of a similar age, while in others their scores had fallen by a similar amount.

As a result, the researchers analysed the brain scans to find out if there was any link to the teenagers IQ scores.

Sue Ramsden, first author of the study, said: "We found a clear correlation between this change in performance and changes in the structure of their brains and so can say with some certainty that these changes in IQ are real."

The researchers suggested the differences seen could be due to some of the teenagers being early or late developers, but it is equally possible that education played a role in changing IQ, and this has implications for how schoolchildren are assessed.

Professor Price said: "It's analogous to fitness. A teenager who is athletically fit at 14 could be less fit at 18 if they stopped exercising. Conversely, an unfit teenager can become much fitter with exercise."

"We have a tendency to assess children and determine their course of education relatively early in life, but here we have shown that their intelligence is likely to be still developing.

"We have to be careful not to write off poorer performers at an early stage when in fact their IQ may improve significantly given a few more years."

The study, which was funded by the Wellcome Trust, is published in Nature.

This article was published on Thu 20 October 2011

Image © Dmitri MIkitenko -

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