Teens' moods may not be the only things that go through swings -- a new study suggests their IQs can go up and down, too.
The research, published in the journal Nature, shows that these changes in IQ are also linked with changes in brain structure.
To come to the conclusion, European researchers tested 33 teens in 2004 when they 12 to 16 years old. Then, the teens took the same tests four years later, when they were 15 to 20 years old. Brain scans were also conducted to examined their brain structure.
Researchers found that there was a difference in IQ scores between 2008 and 2004, with some people's IQs improving by as many as 20 points, and others' falling by the same amount. (The average score on an IQ test falls around 100, according to Science magazine.)
"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," study researcher Cathy Price, of the Wellcome Trust Centre for Neuroimaging, said in a statement. "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 researchers also found that the brain scans corresponded with the changes in IQ. For people whose verbal IQs improved, grey matter in the brain region responsible for articulating speech increased. Meanwhile, for an increase in non-verbal IQ, the grey matter of the brain region associated with hand movements increased.
The results of the study are "really exciting," John Gabrieli, a neuroscientist at the Massachusetts Institute of Technology who was not involved in the study, told Science. "People have thought IQ is fixed or that it becomes stable very early in life, but here is meaningful evidence that variation happens and continues well into adolescence."