Sexual dimorphism in the relationship between brain complexity, volume and general intelligence (g): a cross-cohort study

Abstract

Changes in brain morphology have been reported during development, ageing and in relation to different pathologies. Brain morphology described by the shape complexity of gyri and sulci can be captured and quantified using fractal dimension (FD). This measure of brain structural complexity, as well as brain volume, are associated with intelligence, but less is known about the sexual dimorphism of these relationships. In this paper, sex differences in the relationship between brain structural complexity and general intelligence (g) in two diverse geographic and cultural populations (UK and Indian) are investigated. 3D T1-weighted magnetic resonance imaging (MRI) data and a battery of cognitive tests were acquired from participants belonging to three different cohorts: Mysore Parthenon Cohort (MPC); Aberdeen Children of the 1950s (ACONF) and UK Biobank. We computed MRI derived structural brain complexity and g estimated from a battery of cognitive tests for each group. Brain complexity and volume were both positively corelated with intelligence, with the correlations being significant in women but not always in men. This relationship is seen across populations of differing ages and geographical locations and improves understanding of neurobiological sex-differences.

Fractal dimension of the cortical gray matter outweighs other brain MRI features as a predictor of transition to dementia in patients with mild cognitive impairment and leukoaraiosis

“…The findings of this study further strengthen the evidence that FD provides supplementary information beyond what is offered by other conventional structural features (Free et al, 1996 ; Im et al, 2006 ; Sandu et al, 2008a , b , 2014a , b , 2022 ; King et al, 2009 , 2010 ; Madan and Kensinger, 2016 , 2018 ; Marzi et al, 2018 , 2020 , 2021 , 2022 ; Pantoni et al, 2019 ; Pani et al, 2022 ; Nazlee and Waiter, 2023 ) and has potential relevant practical and diagnostic implications, particularly regarding the MRI evaluation of the cortical GM. Importantly, the FD measurement can be derived from standard, high-resolution 3D T 1 -weighted images commonly included in clinical MRI protocols.…”

Age‐associated sex and asymmetry differentiation in hemispheric and lobar cortical ribbon complexity across adulthood: A UK Biobank imaging study

“…Among several approaches available to calculate FD, the box‐counting method is more widely used due to its robustness and is considered more reliable to analyse fractal objects, the brain being a natural fractal (Farahibozorg et al, 2015 ; Madan & Kensinger, 2016 ; Mustafa et al, 2012 ; Pantoni et al, 2019 ; Sandu, Izard, et al, 2014 ). We used an FD toolbox in MATLAB 2018a based on a box‐counting algorithm which was developed and validated by Sandu, Rasmussen Jr., et al ( 2008 ) and has been used previously (Sandu, Izard, et al, 2014 ; Sandu, Staff, et al, 2014 ) and recently (Sandu et al, 2022 ). Briefly, a fixed grid composed of 3D boxes (i.e., voxels) of edge length ( r ) is overlapped to the brain ROI (parcellated cortical GM), and the number of grid boxes N ( r ) containing at least one voxel belonging to cortical ribbon is counted.…”

Novel Isolation Method Reveals Sex-Specific Composition and Neurotoxicity of Small Extracellular Vesicles in a Mouse Model of Alzheimer’s Disease

“…It is well established that the female brain is different from the male brain, both anatomically and functionally [ 23 ]. These differences indicate that biological sex may have a substantial influence on human cognitive functions, including emotion, memory, and perception, as well as a predisposition to neurodegenerative diseases [ 22 , 24 , 25 ]. To that end, females are at least two-fold more susceptible to Alzheimer’s disease compared to age-matched males [ 26 , 27 ].…”