Sex Differences in Verbal Fluency during Adolescence: A Functional Magnetic Resonance Imaging Study in Gender Dysphoric and Control Boys and Girls

Authors

  • Remi S. Soleman MSc,

    Corresponding author
    1. Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands
    2. Neuroscience Campus Amsterdam, Amsterdam, the Netherlands
    • Department of Medical Psychology and Medical Social Work, VU University Medical Center, Amsterdam, the Netherlands
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    • Both authors contributed equally to this work.
  • Sebastian E.E. Schagen MSc, MD,

    1. Department of Pediatrics, Leiden University, Leiden, the Netherlands
    2. Department of Pediatric Endocrinology, VU University Medical Center, Amsterdam, the Netherlands
    3. Neuroscience Campus Amsterdam, Amsterdam, the Netherlands
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    • Both authors contributed equally to this work.
  • Dick J. Veltman PhD, MD,

    1. Department of Psychiatry, VU University Medical Center, Amsterdam, the Netherlands
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  • Baudewijntje P.C. Kreukels PhD,

    1. Department of Medical Psychology and Medical Social Work, VU University Medical Center, Amsterdam, the Netherlands
    2. Neuroscience Campus Amsterdam, Amsterdam, the Netherlands
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  • Peggy T. Cohen-Kettenis PhD,

    1. Department of Medical Psychology and Medical Social Work, VU University Medical Center, Amsterdam, the Netherlands
    2. Neuroscience Campus Amsterdam, Amsterdam, the Netherlands
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  • Cornelis B. Lambalk PhD, MD,

    1. Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, the Netherlands
    2. Neuroscience Campus Amsterdam, Amsterdam, the Netherlands
    3. Department of Obstetrics and Gynecology, Center for Reproductive Medicine of the University of Ghent, Ghent, Belgium
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  • Femke Wouters MSc, MD,

    1. Department of Pediatrics, Leiden University, Leiden, the Netherlands
    2. Department of Pediatric Endocrinology, VU University Medical Center, Amsterdam, the Netherlands
    3. Neuroscience Campus Amsterdam, Amsterdam, the Netherlands
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  • Henriette A. Delemarre-van de Waal PhD, MD

    1. Department of Pediatrics, Leiden University, Leiden, the Netherlands
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Corresponding Author: Remi S. Soleman, MSc, Department of Medical Psychology and Medical Social Work, VU University Medical Center, de Boelelaan 1118, 1081 HZ Amsterdam, the Netherlands. Tel: +31-20-42685; Fax: +31-20-4443077; E-mail: r.soleman@vumc.nl/DJ.Veltman@vumc.nl

Abstract

Introduction

In the literature, verbal fluency (VF) is generally described as a female-favoring task. Although it is conceivable that this sex difference only evolves during adolescence or adulthood under influence of sex steroids, this has never been investigated in young adolescents.

Aim

First, to assess sex differences in VF performance and regional brain activation in adolescents. Second, to determine if untreated transsexual adolescents differ from their sex of birth with regard to VF performance and regional brain activation.

Method

Twenty-five boys, 26 girls, 8 Male-to-Female transsexual adolescents (MtFs), and 14 Female-to-Male transsexual adolescents (FtMs) were tested in a cross-sectional study, while performing a phonetic and semantic VF task within an MRI scanner.

Main Outcome Measures

Functional MRI response during VF task.

Results

Boys and girls produced similar amounts of words, but the group MtFs produced significantly more words in the phonetic condition compared to control boys, girls, and FtMs. During the semantic condition, no differences were found. With regard to brain activity, control boys showed more activation in the right Rolandic operculum, a small area adjacent to Broca's area, compared to girls. No significant differences in brain activity were found comparing transsexual adolescents, although sub-threshold activation was found in the right Rolandic operculum indicating a trendwise increase in activation from control girls to FtMs to MtFs to control boys.

Conclusions

The better performance of MtFs is consistent with our expectation that MtFs perform better on female-favoring tasks. Moreover, they produced more words than girls and FtMs. Even though a trendwise linear increase in brain activity between the four groups only approached significance, it may indicate differences in individuals with gender identity disorder compared to their birth sex. Although our findings should thus be interpreted with caution, they suggest a biological basis for both transgender groups performing in-between the two sexes. Soleman RS, Schagen SEE, Veltman DJ, Kreukels BPC, Cohen-Kettenis PT, Lambalk CB, Wouters F, and Delemarre-van de Waal HA. Sex differences in verbal fluency during adolescence: A functional magnetic resonance imaging study in gender dysphoric and control boys and girls. J Sex Med 2013;10:1969–1977.

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