New evidence confirms link between IQ, brain cortex

March 4, 2014
Science Daily/McGill University
Rate of change in the thickness of the brain's cortex is an important factor associated with a person's change in IQ, according to a collaborative study by scientists in five countries. The cortex is the thin, outermost layer of nerve cell tissue of the brain, typically measuring a few millimeters in thickness. The cortex contains nerve cell bodies and is critical for cognitive functions such as perception, language, memory and consciousness. The cortex begins to thin after the age of five or six as part of the normal aging process. This study is the first to show the association between cortical thickness and development in full scale IQ, and has potentially wide-ranging implications for the pedagogical world and for judicial cases in which the defendant's IQ score could play a role in determining the severity of the sentence.

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Finding that IQ is not fixed and correlates to changes in brain anatomy has important implications as it shows that some of the changes in IQ are real and not merely due to measurement error. This finding should make people wary of sticking to an early IQ assessment given the role it plays in school entrance criteria, detection of the gifted, as well as in eligibility for social security disability income or even the death penalty. In some US states, people with an IQ below 70 are not eligible for the death penalty."

The reasons behind the changes in IQ are not clear at this point. Some of these may be due to programmed developmental trajectories or other factors such as nutrition and education, noted Professor Karama.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2014/03/140304141734.htm