IQ is not fixed in the teenage brain, new research finds

Published 5:00 am Friday, October 21, 2011

A new study confirms what parents have long suspected: Adolescence can do a number on kids’ brains. Researchers have found that IQ can rise or fall during the teen years and that the brain’s structure reflects this uptick or decline. The result offers the first direct evidence that intelligence can change after early childhood and provides new hope for boosting the brain’s abilities.

Although researchers debate what IQ tests actually measure, they agree that scores can predict our ability to learn and perform certain tasks, and to some degree forecast our later academic achievement and job performance. Scores have long been thought to stay relatively stable throughout our lives; the few studies that have shown some variation in IQ could not rule out measurement errors or differences in testing environment as the cause.

So neuroscientist Cathy Price of University College London and colleagues looked beyond the scores. They tested 33 teenagers — 19 boys and 14 girls — in 2004, when they were 12 to 16 years old, and again in 2008, when they were 15 to 20 years old. Each time, the teens took IQ tests that measured their verbal and nonverbal abilities. Then, using magnetic resonance imaging, the researchers scanned the teenagers’ brains while they performed verbal tasks, such as reading or naming objects, and nonverbal tasks, such as solving visual puzzles with their hands. The idea was to match their test scores with a picture of their brain’s structure and activity at each time.

The test results revealed dramatic changes: between their first testing and their second, the teens’ verbal and nonverbal IQ scores rose or fell by as many as 20 points (on a scale for which the average is 100). Some teens improved or declined in just their verbal or nonverbal skills or improved in one area and declined in the other.

“These changes are real and they are reflected in the brain,” says Price, whose team reports the finding online today in Nature.