Low Prevalence of Mixed Dementia in a Cohort of 2,000 Elderly Patients in a Memory Clinic Setting

Article type: Research Article

Authors: Claus, Jules J.^a | Staekenborg, Salka S.^{a; f} | Roorda, Jelmen J.^a | Stevens, Martijn^a | Herderschee, Dirk^a | van Maarschalkerweerd, Willy^b | Schuurmans, Lilly^b | Tielkes, Caroline E.M.^c | Koster, Pieter^d | Bavinck, Chris^e | Scheltens, Philip^{f; *}

Affiliations: [a] Department of Neurology, Tergooi Hospitals, Blaricum, The Netherlands | [b] Department of Geriatrics, Tergooi Hospitals, Blaricum, The Netherlands | [c] Department of Medical neuropsychology, Tergooi Hospitals, Blaricum, The Netherlands | [d] Department of Radiology, Tergooi Hospitals, Blaricum, The Netherlands | [e] GGZ-centraal, Hilversum, The Netherlands | [f] Alzheimer Center, Department of Neurology, VU University Medical Center, Neuroscience Campus Amsterdam, Amsterdam, The Netherlands

Correspondence: [*] Correspondence to: Philip Scheltens, Alzheimer Center PK -1 Z 44, VU University Medical Center, de Boelelaan 1118, 1081 HZ Amsterdam, The Netherlands. Tel.:+31 20 4440816; Fax+31 20 4440715; E-mail: p.scheltens@vumc.nl.

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. Conclusion:We found a low prevalence of mixed dementia. Furthermore, severe WML in AD was largely explained by age rather than effect of disease.

Keywords: Alzheimer’s disease, computed tomography, Fazekas score, memory clinic, white matter lesions

DOI: 10.3233/JAD-150796

Journal: Journal of Alzheimer's Disease, vol. 50, no. 3, pp. 797-806, 2016