A teen's IQ is not set in stone, according to a new study published in Nature. Instead, the standard measure of intelligence -- often used to predict future success -- can fluctuate dramatically.
"The results indicate that an early developer doesn't necessarily continue to excel; and a late developer can catch up. Educators already know this," study researcher Cathy Price, PhD, tells WebMD in an email. "The more relevant point is that, if IQ changes are real (as we claim), they are not measuring a capacity to do well. They are measuring how well the individual is doing at a fixed time."
Price, a professor at the Wellcome Trust Centre for Neuroimaging at University College London, and colleagues, tested 33 "healthy and neurologically normal" adolescents aged 12 to 16. Their IQ scores ranged from 77 to 135, with an average score of 112.
Four years later, the same group took another IQ test. While the average score of 113 was only one point greater than the previous test, the range of scores was quite different: 87 to 143. Individually, the results were quite striking, as participants showed as much as an 18-point drop in IQ, while others shot up as high as 21 points.
Overall, the researchers report, one-fifth of the kids tested moved from one IQ category to another, from average to below average, for example.
Each of the participants also underwent brain scans -- a combination of functional and structural imaging -- at the time that they were given the IQ tests, which confirmed the researchers' findings that the changes in test scores are likely real.
One important finding, Price points out, is that teens, whether they test high or low, appear to have an equal capacity to change -- for better or for worse.