Genetic associations between intelligence and cortical thickness emerge at the start of puberty

Authors

  • Rachel M. Brouwer,

    Corresponding author
    1. Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands
    • Correspondence to: Rachel M. Brouwer, Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands. E-mail: r.m.brouwer-4@umcutrecht.nl

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  • Inge L.C. van Soelen,

    1. Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands
    2. Department of Biological Psychology, VU University Amsterdam, Amsterdam, The Netherlands
    Current affiliation:
    1. Department of Public Health and Primary Care, Leiden University Medical Center, Leiden, The Netherlands
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  • Suzanne C. Swagerman,

    1. Department of Biological Psychology, VU University Amsterdam, Amsterdam, The Netherlands
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  • Hugo G. Schnack,

    1. Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands
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  • Erik A. Ehli,

    1. Avera Institute for Human Genetics, Avera Behavioral Health Center, Sioux Falls, South Dakota
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  • René S. Kahn,

    1. Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands
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  • Hilleke E. Hulshoff Pol,

    1. Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands
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  • Dorret I. Boomsma

    1. Department of Biological Psychology, VU University Amsterdam, Amsterdam, The Netherlands
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  • Rachel M. Brouwer and Inge L.C. van Soelen contributed equally to this work.

  • Hilleke E. Hulshoff Pol and Dorret I. Boomsma contributed equally to this work.

Abstract

Cognitive abilities are related to (changes in) brain structure during adolescence and adulthood. Previous studies suggest that associations between cortical thickness and intelligence may be different at different ages. As both intelligence and cortical thickness are heritable traits, the question arises whether the association between cortical thickness development and intelligence is due to genes influencing both traits. We study this association in a longitudinal sample of young twins. Intelligence was assessed by standard IQ tests at age 9 in 224 twins, 190 of whom also underwent structural magnetic resonance imaging (MRI). Three years later at age 12, 177/125 twins returned for a follow-up measurement of intelligence/MRI scanning, respectively. We investigated whether cortical thickness was associated with intelligence and if so, whether this association was driven by genes. At age 9, there were no associations between cortical thickness and intelligence. At age 12, a negative relationship emerged. This association was mainly driven by verbal intelligence, and manifested itself most prominently in the left hemisphere. Cortical thickness and intelligence were explained by the same genes. As a post hoc analysis, we tested whether a specific allele (rs6265; Val66Met in the BDNF gene) contributed to this association. Met carriers showed lower intelligence and a thicker cortex, but only the association between the BDNF genotype and cortical thickness in the left superior parietal gyrus reached significance. In conclusion, it seems that brain areas contributing to (verbal) intellectual performance are specializing under the influence of genes around the onset of puberty. Hum Brain Mapp 35:3760–3773, 2014. © 2013 Wiley Periodicals, Inc.

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