Friday, October 21, 2011

Brain scans support findings that IQ can rise or fall significantly during adolescence

IQ, the standard measure of intelligence, can increase or fall significantly during our teenage years, according to research funded by the Wellcome Trust, and these changes are associated with changes to the structure of our brains. The findings may have implications for testing and streaming of children during their school years.

Across our lifetime, our intellectual ability is considered to be stable, with Intelligence Quotient (IQ) scores taken at one point in time used to predict educational achievement and employment prospects later in life. However, in a study published today in the journal Nature, researchers at the Wellcome Trust Centre for Neuroimaging at UCL (University College London) and the Centre for Educational Neuroscience show for the first time that in fact our IQ is not constant.

The researchers, led by Professor Cathy Price, tested thirty-three healthy adolescents in 2004 when they were between the ages of 12 and 16 years. They then repeated the tests four years later when the same subjects were between 15 and 20 years old. On both occasions, the researchers took structural brains scans of the subjects using magnetic resonance imaging (MRI).

Professor Price and colleagues found significant changes in the IQ scores measured in 2008 compared to the 2004 scores. Some subjects had improved their performance relative to people of a similar age by as much as 20 points on the standardised IQ scale; in other cases, however, performance had fallen by a similar amount. In order to test whether these changes were meaningful, the researchers analysed the MRI scans to see if there was a correlation with changes in the structure of the subjects' brains.

"We found a considerable amount of change in how our subjects performed on the IQ tests in 2008 compared to four years earlier," explains Sue Ramsden, first author of the study. "Some subjects performed markedly better but some performed considerably worse. 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."

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