Sexual Dimorphism in Healthy Aging and Mild Cognitive Impairment: A DTI Study

Abstract

Previous PET and MRI studies have indicated that the degree to which pathology translates into clinical symptoms is strongly dependent on sex with women more likely to express pathology as a diagnosis of AD, whereas men are more resistant to clinical symptoms in the face of the same degree of pathology. Here we use DTI to investigate the difference between male and female white matter tracts in healthy older participants (24 women, 16 men) and participants with mild cognitive impairment (21 women, 12 men). Differences between control and MCI participants were found in fractional anisotropy (FA), radial diffusion (DR), axial diffusion (DA) and mean diffusion (MD). A significant main effect of sex was also reported for FA, MD and DR indices, with male control and male MCI participants having significantly more microstructural damage than their female counterparts. There was no sex by diagnosis interaction. Male MCIs also had significantly less normalised grey matter (GM) volume than female MCIs. However, in terms of absolute brain volume, male controls had significantly more brain volume than female controls. Normalised GM and WM volumes were found to decrease significantly with age with no age by sex interaction. Overall, these data suggest that the same degree of cognitive impairment is associated with greater structural damage in men compared with women.

Brain white matter structural properties predict transition to chronic pain

“…Reported results are consistent across labs and generally show that FA, especially in frontal cortex white matter, decreases by about 0.1 over a 60-year age range, and whole-brain skeletal FA decreases by about 0.03 over a 30 year age difference [14; 22; 29; 37]. As the mean age of all three subject groups studied here were within a 10 year range and SBP subgroups showed small but significant age differences, throughout this study we used age as a confound of no interest.…”

“…Multiple studies indicate that white matter FA decreases with aging [14; 22; 29; 37]. Reported results are consistent across labs and generally show that FA, especially in frontal cortex white matter, decreases by about 0.1 over a 60-year age range, and whole-brain skeletal FA decreases by about 0.03 over a 30 year age difference [14; 22; 29; 37].…”

Heritability of fractional anisotropy in human white matter: A comparison of Human Connectome Project and ENIGMA-DTI data

“…The HCP recruitment was designed to reduce the effects of age on the brain measurements by limiting recruitment to age-range that corresponds to a plateau in FA-aging trend (22–35 years) (Kochunov et al, 2011; Van Essen et al, 2013). Significant sex differences in the average and regional FA values are commonly reported (Bava et al, 2010; Menzler et al, 2010; O’Dwyer et al, 2013; Wang et al, 2012), however, the direction and size of this effect vary from study to study (den Braber et al, 2013). High heritability values and modest effects of covariates posit HCP cohort for further studies of genetic effects on normal variability in cerebral white matter.…”

Classification of mild cognitive impairment and Alzheimer’s Disease with machine-learning techniques using 1H Magnetic Resonance Spectroscopy data

“…All these works are based on anatomical MR imaging (MRI) biomarkers, such as volumetric or cortical thickness measures, to help discriminate AD subjects from elderly control or MCI subjects. However, other MR techniques, such as Diffusion Tensor Imaging (DTI), have been explored in the automatic classification of MCI patients (Haller et al, 2010;O'Dwyer et al, 2012, M. Dyrba et al, 2013b. The collection of Weka machine-learning algorithms (Hall et al, 2009) was also used for the learning and classification processes in the detection of microstructural white matter degeneration in AD with DTI (M. Dyrba et al, 2013a) and for the detection of brain atrophy patterns based on MRI for the prediction and early detection of AD (Farhan, et al, 2014;Plant, et al, 2010).…”