Abstract 2363: Are White Matter Lesions Associated with Deep or Superficial Brain Atrophy or both?
Introduction White matter lesions (WMLs) are associated with cognitive decline, dementia and increased risk of stroke. Cerebral atrophy is also associated with future cognitive impairment and dementia. Both WMLs and atrophy are commonly found on MRI scans of elderly people, but whether they are related, and the strength of any relationship remains unclear.
Hypotheses We hypothesised that 1) WMLs are associated with brain atrophy, 2) are more associated with deep (white matter) than superficial (cortical) atrophy, and 3) the association is similar for volumetric and visually rated WMLs.
Methods We performed structural brain MRI on subjects from the Lothian Birth Cohort 1936 (www.lothianbirthcohort.ed.ac.uk) and measured intracranial (ICV), brain tissue (BTV), CSF ventricular, superficial subarachnoid space (SSS), grey matter (GM), normal appearing white matter (NAWM) and WML volumes using validated software (MCMxxxVI, http://sourceforge.net/projects/bric1936/). We also measured CSF + venous sinuses (V) + dural (D) volume (CSF+V+D) combined to further assess ICV changes due to brain atrophy and rated WMLs using the Fazekas scale. We used Spearman partial correlation to test associations between WMLs and brain atrophy, controlled for gender and ICV and performed general linear modelling (GLM).
Results Amongst 672 subjects, mean age 73±1year, greater WML volume correlated: with reduced BTV (r=-0.10, P=0.01) and NAWM (r= -0.15, P<0.01), increased ventricular volume (r= 0.11, P<0.01) and CSF+V+D (r=0.11, P=0.01) but not with SSS (r=0.03, P=0.39), GM (r=-0.07, P=0.09) or CSF (r=0.06, P=0.13). A 1mm3 increase in WML volume was associated with 0.43mm3 decrease in BTV. We found similar associations for Fazekas WML scores. Gender and original brain size (i.e. ICV) explained 77.6% and 23.8% of the variance in BTV and ventricular volume, respectively, but WMLs explained <1% of either (GLM).
Conclusions WMLs, assessed using both measured volumes and visual rating scales, are associated with brain atrophy mostly through deep white matter loss. Studies of brain atrophy in ageing or dementia should assess venous sinuses, dura and CSF, not just CSF, as sinuses and dura expand to occupy space left by brain atrophy. Further work to determine causes of age-related brain atrophy is required as WMLs only explain a small proportion of it.
- © 2012 by American Heart Association, Inc.