Elsevier

NeuroImage

Volume 36, Issue 4, 15 July 2007, Pages 1065-1073
NeuroImage

Sexual dimorphism of brain developmental trajectories during childhood and adolescence

https://doi.org/10.1016/j.neuroimage.2007.03.053Get rights and content

Abstract

Human total brain size is consistently reported to be ∼ 8–10% larger in males, although consensus on regionally specific differences is weak. Here, in the largest longitudinal pediatric neuroimaging study reported to date (829 scans from 387 subjects, ages 3 to 27 years), we demonstrate the importance of examining size-by-age trajectories of brain development rather than group averages across broad age ranges when assessing sexual dimorphism. Using magnetic resonance imaging (MRI) we found robust male/female differences in the shapes of trajectories with total cerebral volume peaking at age 10.5 in females and 14.5 in males. White matter increases throughout this 24-year period with males having a steeper rate of increase during adolescence. Both cortical and subcortical gray matter trajectories follow an inverted U shaped path with peak sizes 1 to 2 years earlier in females. These sexually dimorphic trajectories confirm the importance of longitudinal data in studies of brain development and underline the need to consider sex matching in studies of brain development.

Introduction

The degree to which sexual dimorphism extends to human brain anatomy has been the subject of many investigations, with most reporting total brain size to be ∼ 8–10% larger in males (Goldstein et al., 2001). However, the literature is notably inconsistent as to which subcomponents of the brain differ after accounting for the total brain size difference. Discrepant findings in sexual dimorphism studies may be partially accounted for by subject age, with some studies combining subjects across several decades. There is a particular paucity of data on sexual dimorphism of human brain anatomy between 4 and 22 years of age, a time of emerging sex differences in behavior and cognition (Cairns et al., 1985, Gouchie and Kimura, 1991, Johnson and Meade, 1987). Large individual variation in brain morphometry makes accurate characterization of developmental trajectories difficult with cross-sectional studies (Giedd et al., 1996c, Kraemer et al., 2000).

We compared trajectories of male and female brain development using longitudinal MRI data from healthy children and adolescents. Measures included gray and white volumes for the total cerebrum, frontal, temporal, parietal, and occipital lobes, volumes of the caudate nucleus and lateral ventricles, and corpus callosal area. Trajectories were compared by shape and by volume at the mean age.

Section snippets

Subject selection

Subjects were healthy singleton or twin participants in an ongoing study at the Child Psychiatry Branch of the National Institute of Mental Health which began in 1989. Singleton subjects were recruited from the local community; twin subjects were recruited nationally. Only one subject from each family was included in the study; one member of each twin pair was chosen at random.

Healthy controls were screened via previously published criteria (Giedd et al., 1996a) which included an initial

Results

Robust sex differences in developmental trajectories were noted for nearly all structures with peak gray matter volumes generally occurring earlier for females. A representative scatterplot showing raw data for total brain volume and modeled developmental trajectories are presented in Fig. 1, Fig. 2, Fig. 3. A summary of relevant statistical analysis is presented in Table 3, Table 4.

Consistent with previous investigations (Giedd et al., 1999), mean total cerebral volume was approximately 10%

Discussion

Here we have demonstrated the importance of considering trajectories rather than group averages across broad age spans in investigations of brain sexual dimorphism. The finding that sex differences were age-dependent may partially account for discrepant findings of sexual dimorphism in the literature.

Previous work comparing brain growth patterns between males and females has been sparse and limited by small sample sizes or cross-sectional designs. In a cross-sectional sample of 118 healthy

Acknowledgments

RL and JG wrote the paper and oversaw data acquisition and analysis. JG conceived the study. NG was involved in acquiring and interpreting the data. AZ, JL, AE, JB, and CV were involved in analyzing the images. EM and GW were involved in subject recruitment and screening. DG and LC conducted the statistical analysis. PT was involved in image analysis and data interpretation.

References (33)

  • R.E. Dahl

    Adolescent brain development: a period of vulnerabilities and opportunities. Keynote address

    Ann. N. Y. Acad. Sci.

    (2004)
  • M.D. De Bellis et al.

    Sex differences in brain maturation during childhood and adolescence

    Cereb. Cortex

    (2001)
  • A.S. Dekaban et al.

    Changes in brain weight during the span of human life: relation of brain weights to body heights and body weights

    Ann. Neurol.

    (1978)
  • P.J. Diggle et al.

    Analysis of Longitudinal Data

    (1994)
  • A.C. Evans

    Large-scale morphometric analysis of neuroanatomy and neuropathology

    Anat. Embryol. (Berl)

    (2005)
  • A. Fausto-Sterling

    Myths of Gender: Biological Theories About Women and Men

    (1992)
  • Cited by (0)

    This research was supported [in part] by the Intramural Program of the NIH, NIMH.

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