Review: magnetic resonance imaging of male/female differences in human adolescent brain anatomy
1 Child Psychiatry Branch, Brain Imaging Unit, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, MSC 1367, Building 10, Room 4 C110, Bethesda, MD, 20892, USA
2 Department of Psychiatry, University of New South Wales, Sydney, NSW, Australia
3 Institute of Cognitive Neuroscience, University College London, London, UK
Biology of Sex Differences 2012, 3:19 doi:10.1186/2042-6410-3-19Published: 21 August 2012
Improvements in neuroimaging technologies, and greater access to their use, have generated a plethora of data regarding male/female differences in the developing brain. Examination of these differences may shed light on the pathophysiology of the many illnesses that differ between the sexes and ultimately lead to more effective interventions. In this review, we attempt to synthesize the anatomic magnetic resonance imaging (MRI) literature of male/female brain differences with emphasis on studies encompassing adolescence – a time of divergence in physical and behavioral characteristics. Across all ages total brain size is consistently reported to be about 10% larger in males. Structures commonly reported to be different between sexes include the caudate nucleus, amygdala, hippocampus, and cerebellum – all noted to have a relatively high density of sex steroid receptors. The direction and magnitude of reported brain differences depends on the methodology of data acquisition and analysis, whether and how the subcomponents are adjusted for the total brain volume difference, and the age of the participants in the studies. Longitudinal studies indicate regional cortical gray matter volumes follow inverted U shaped developmental trajectories with peak size occurring one to three years earlier in females. Cortical gray matter differences are modulated by androgen receptor genotyope and by circulating levels of hormones. White matter volumes increase throughout childhood and adolescence in both sexes but more rapidly in adolescent males resulting in an expanding magnitude of sex differences from childhood to adulthood.