(CBS) If you think intelligence is set in stone, think again.
A new study shows that IQ can fluctuate dramatically during adolescence, with some teens raising or lowering their scores by about 20 points.
Psychologists have long believed that intelligence was fixed, and parents and educators often use IQ scores to determine whether children are "gifted" or need extra help at school. But the study suggests things are a bit more complicated.
For the study - published in the Oct. 18 issue of Nature - British researchers gave IQ tests to 33 children between the ages of 12 and 16. Four years later, researchers re-tested the same adolescents and found that about one-fifth of the kids fluctuated from one IQ category to another - such as from average to above-average intelligence, or vice versa. Some students' IQ rose as high as 21 points, while others fell by up to 18 points.
"A change in 20 points is a huge difference," study author Professor Cathy Price, a senior research fellow at Wellcome Trust Centre for Neuroimaging in the U.K, told WebMD. "If an individual moved from an IQ of 110 to an IQ of 130, they move from being 'average' to 'gifted.' And if they moved from 104 to 84, they move from being high average to below average."
Brain scans of the children confirmed that changes in IQ were mirrored by structural changes in the brain. That led the researchers to say that "these changes in IQ are real," study co-author Dr. Sue Ramsden, research assistant at Wellcome Trust, said in a written statement.
What's behind the rise or fall in brainpower? The authors said more research is needed to pinpoint the cause, but indicated that some children might simply be early or late bloomers. So parents shouldn't be so quick to give up on a seemingly dim-witted kid - or assume their smart child is set for life.
"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," Price said in the statement.
Price said in the statement that adults as well as youngsters could show changes in intelligence.
Will this study change the way you look at IQ tests?