title: Low Prevalence of Mixed Dementia in a Cohort of 2,000 Elderly Patients in a Memory Clinic Setting.
abstract: BACKGROUND
  It is generally assumed that with increasing age, pathology in clinically diagnosed Alzheimer's disease (AD) becomes more mixed, i.e., co-existence of amyloid plaques and cerebrovascular pathology.
  
  
  OBJECTIVE
  To test the hypothesis of increasing prevalence of mixed dementia in late-onset clinically diagnosed Alzheimer's disease (AD) in a single-center memory clinic population.
  
  
  METHODS
  Patients included had diagnoses of AD (n = 832), subjective cognitive impairment (SCI, n = 333), mild cognitive impairment (MCI, n = 492), vascular dementia (VaD, n = 57), other dementia (n = 53), or other diagnosis (n = 233). Prevalence of severe white matter lesions (WML) was defined as a score of 2 or higher on the Fazekas-scale on brain computed tomography to classify AD patients as having mixed dementia. We examined the effect of age on WML using multiple linear regression analysis, and AD patients were compared to SCI to determine the effect of disease on WML.
  
  
  RESULTS
  Prevalence of severe WML was 33.6% in AD patients (mixed dementia), 11.4% in SCI, 22.7% in MCI, 75.4% in VaD, 3.8% in other dementia, and 15.5% in other diagnosis. With increasing age there was a significant and similar increase of WML scores in SCI, MCI, AD, other dementia, and other diagnosis, indicating no effect modification by AD. The difference between AD patients and SCI averaged 0.16 on the WML score and difference in percentage severe WML between AD and SCI patients was 15% across all ages.
  
  
  CONCLUSIONS
  We found a low prevalence of mixed dementia. Furthermore, severe WML in AD was largely explained by age rather than effect of disease.
authors.affiliation: Department of Neurology, Tergooi Hospitals, Blaricum, The Netherlands.
authors.forename: Jules J
authors.initials: JJ
authors.lastname: Claus
authors.affiliation: Department of Neurology, Tergooi Hospitals, Blaricum, The Netherlands.|Alzheimer Center, Department of Neurology, VU University Medical Center, Neuroscience Campus Amsterdam, Amsterdam, The Netherlands.
authors.forename: Salka S
authors.initials: SS
authors.lastname: Staekenborg
authors.affiliation: Department of Neurology, Tergooi Hospitals, Blaricum, The Netherlands.
authors.forename: Jelmen J
authors.initials: JJ
authors.lastname: Roorda
authors.affiliation: Department of Neurology, Tergooi Hospitals, Blaricum, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Stevens
authors.affiliation: Department of Neurology, Tergooi Hospitals, Blaricum, The Netherlands.
authors.forename: Dirk
authors.initials: D
authors.lastname: Herderschee
authors.affiliation: Department of Geriatrics, Tergooi Hospitals, Blaricum, The Netherlands.
authors.forename: Willy
authors.initials: W
authors.lastname: van Maarschalkerweerd
authors.affiliation: Department of Geriatrics, Tergooi Hospitals, Blaricum, The Netherlands.
authors.forename: Lilly
authors.initials: L
authors.lastname: Schuurmans
authors.affiliation: Department of Medical neuropsychology, Tergooi Hospitals, Blaricum, The Netherlands.
authors.forename: Caroline E M
authors.initials: CE
authors.lastname: Tielkes
authors.affiliation: Department of Radiology, Tergooi Hospitals, Blaricum, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: Koster
authors.affiliation: GGZ-centraal, Hilversum, The Netherlands.
authors.forename: Chris
authors.initials: C
authors.lastname: Bavinck
authors.affiliation: Alzheimer Center, Department of Neurology, VU University Medical Center, Neuroscience Campus Amsterdam, Amsterdam, The Netherlands.
authors.forename: Philip
authors.initials: P
authors.lastname: Scheltens
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000453:epidemiology*; D015331:Cohort Studies; D003704:Dementia / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D015995:Prevalence; D012044:Regression Analysis; D012307:Risk Factors; D015898:Tomography Scanners, X-Ray Computed
keywords: Alzheimer’s disease; Fazekas score; computed tomography; memory clinic; white matter lesions