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No, Your IQ Is Not Constant

The implications are profound.

Common wisdom asserts that your IQ is fixed. Of course, the various “multiple intelligences” change with personal life experiences and growth, but we usually consider the standard IQ score to be inherent and unchangeable.

But even the standard IQ measure changes during different life stages. Clearly, the IQ of young children changes as they mature. Several studies even show that working-memory training can raise the IQ of elementary-school children. More than one analyst claims that a rigorous Ph.D. program can raise IQ in adults. Most obvious is the decline of IQ in those elderly who do not age well because of disease.

A neglected segment along the age spectrum is the teenage years. Now, evidence indicates that this age group experiences IQ changes ranging from a decline to an increase. A study of this issue shows that both verbal and non-verbal IQ scores in teenagers relate closely to the developmental changes that occur in brain structure during the teenage years. Longitudinal brain-imaging studies in the same individuals reveal that either increases or decreases in IQ occur coincident with structural changes in cerebral grey matter that occur in teenagers.

The study conducted MRI brain scans and IQ tests on 33 normal adolescents in early teenage years and then again in late teenage years. A wide range of IQs were noted, 77 to 135 in the early group and 87 to 143 in the late group. For any given individual, the change in IQ score changed from -20 to +23 for verbal IQ and -28- to +17 for non-verbal IQ. Correlation analysis revealed that increases in IQ were associated with increased in cortical density and volume for brain regions involved in verbal and movement functions.

The implications are profound, especially as they relate to the local environment of a given teenager. What happens during the teenager years apparently changes brain structure and mental ability. Many influences likely damage the brain, such as drug abuse, or social stress, or poor education and intellectual stimulation. Conversely, the data indicate that positive benefits to both brain structure and mental capability can result from a mentally healthy environment and rich educational experience.

The data suggest that all the emphasis on pre-school and “Head Start” initiatives may diminish our attention to the key role played by middle school and early high school. This confirms what many of us always suspected, namely that our society tends to insufficiently nurture “late bloomers.” Maybe the early high achievers who fail to live up to their promise do so, because we wrongly assume they can manage without much help. Parents, educators, and education policy makers need to take notice.

Few books can change a person's future. One of them could be my book, Better Grades, Less Effort, which explains the learning tips and tricks that I used to become valedictorian, when a high school teacher said my modest IQ did not justify the high grades I was making. Teachers predicted I "would have trouble with college." Really? I went on to be an Honors student in three universities — including graduating early with a D.V.M. degree and securing a Ph.D. in two and a half years. My IQ documented that I was not so smart. I believe that poor learning skills are what hold back most students from superior achievement. This book can change a person's life, as my own experiences with learning how to learn have changed my life. I suspect it helped my brain development as well.


Ramsden, Sue et al. (2011). Verbal and non-verbal intelligence changes in the teenage brain. Nature. May 17. Doi:10:1038/nature10514.

More from William R. Klemm Ph.D.
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