title: Do cerebral white matter lesions influence the rate of progression from mild cognitive impairment to dementia?
abstract: BACKGROUND
  Cerebral white matter lesions (WML), evident on CT and MRI brain scans, are histopathologically heterogeneous but associated with vascular risk factors and thought mainly to indicate ischemic damage. There has been disagreement over their clinical prognostic value in predicting conversion from mild cognitive impairment (MCI) to dementia.
  
  
  METHODS
  We scrutinised and rated CT and MRI brain scans for degree of WML in a memory clinic cohort of 129 patients with at least 1 year of follow-up. We examined the relationship between WML severity and time until conversion to dementia for all MCI patients and for amnestic (aMCI) and non-amnestic (naMCI) subgroups separately.
  
  
  RESULTS
  Five-year outcome data were available for 87 (67%) of the 129 patients. The proportion of patients converting to dementia was 25% at 1 year and 76% at 5 years. Patients with aMCI converted to dementia significantly earlier than those with naMCI. WML severity was not associated with time to conversion to dementia for either MCI patients in general or aMCI patients in particular. Among naMCI patients, there was a tendency for those with a low degree of WML to survive without dementia for longer than those with a high degree of WML. However, this was not statistically significant.
  
  
  CONCLUSIONS
  MCI subtype is a significant independent predictor of conversion to dementia, with aMCI patients having higher risk than naMCI for conversion throughout the 5-year follow-up period. WML severity does not influence conversion to dementia for aMCI but might accelerate progression in naMCI.
authors.affiliation: North East London NHS Foundation Trust, Broad Street Centre, Morland Road, Dagenham, Essex RM10 9HU, UK. mike.devine@nelft.nhs.uk
authors.forename: Michael E
authors.initials: ME
authors.lastname: Devine
authors.forename: J Andres Saez
authors.initials: JA
authors.lastname: Fonseca
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Walker
mesh_terms: D000368:Aged; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology*; D060825:Cognitive Dysfunction / Q000473:pathology*; D003704:Dementia / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D059906:Neuroimaging; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed