A meta-analysis of sex differences in human brain structure

Amber N.V Ruigrok,Gholamreza Salimi-Khorshidi,Meng-Chuan Lai,Simon Baron-Cohen,Michael V Lombardo,Roger J Tait,John Suckling

doi:10.1016/j.neubiorev.2013.12.004

Abstract

The prevalence, age of onset, and symptomatology of many neuropsychiatric conditions differ between males and females. To understand the causes and consequences of sex differences it is important to establish where they occur in the human brain. We report the first meta-analysis of typical sex differences on global brain volume, a descriptive account of the breakdown of studies of each compartmental volume by six age categories, and whole-brain voxel-wise meta-analyses on brain volume and density. Gaussian-process regression coordinate-based meta-analysis was used to examine sex differences in voxel-based regional volume and density. On average, males have larger total brain volumes than females. Examination of the breakdown of studies providing total volumes by age categories indicated a bias towards the 18–59 year-old category. Regional sex differences in volume and tissue density include the amygdala, hippocampus and insula, areas known to be implicated in sex-biased neuropsychiatric conditions. Together, these results suggest candidate regions for investigating the asymmetric effect that sex has on the developing brain, and for understanding sex-biased neurological and psychiatric conditions.

Highlights

The prevalence, age of onset, and symptomatology of many neurological and psychiatric conditions differ substantially between males and females (Bao and Swaab, 2010; Baron-Cohen et al, 2011; Central Brain Tumour Registry of the United States, 2012; Paus et al, 2008; Rutter et al, 2003)
As development and ageing have a large influence on total brain volume, we investigated if different age categories were well represented in the literature by providing a description of the number of articles, number of total participants and weighted mean volume of each compartmental volume for each of the six age categories
We explored the question that if male and female brains differ, do such areas of differences overlap with areas commonly implicated in psychiatric conditions? We found that across a wide age range, from newborns to individuals over 80 years old, differences in overall brain volumes are sustained between males and females

Summary

Introduction

The prevalence, age of onset, and symptomatology of many neurological and psychiatric conditions differ substantially between males and females (Bao and Swaab, 2010; Baron-Cohen et al, 2011; Central Brain Tumour Registry of the United States, 2012; Paus et al, 2008; Rutter et al, 2003). Factors influencing the asymmetric effect that sex has on brain development may help us understand how and why male and female brains differ in their predisposition for risk for or resilience to such conditions. Identifying where and in what way male and female brains differ will help illuminate these factors and associated mechanisms. We report the first meta-analysis of overall and voxel-wise regional brain structure of sex differences in the typically developing human brain and provide a descriptive account of the breakdown of studies providing overall volumes by age category

Methods

Results

Discussion

Conclusion