Neuropsychological Syndromes Associated with Alzheimer's/Vascular Dementia: A Latent Class Analysis

Article type: Research Article

Authors: Libon, David J.^{a; *} | Drabick, Deborah A.G.^b | Giovannetti, Tania^b | Price, Catherine C.^c | Bondi, Mark W.^d | Eppig, Joel^a | Devlin, Kathryn^b | Nieves, Christine^a | Lamar, Melissa^e | Delano-Wood, Lisa^d | Nation, Daniel A.^f | Brennan, Laura^a | Au, Rhoda^g | Swenson, Rod^h

Affiliations: [a] Department of Neurology, Drexel University, College of Medicine, Philadelphia, PA, USA | [b] Department of Psychology, Temple University, Philadelphia, PA, USA | [c] Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA | [d] Department of Psychiatry, University of California San Diego, School of Medicine, San Diego, CA, USA and The Psychology Service VA San Diego Healthcare System, San Diego, CA, USA | [e] Department of Psychiatry, University of Illinois, Chicago, IL, USA | [f] Department of Psychology, University of Southern California, Los Angeles, CA, USA | [g] Department of Neurology, Boston University and the Framingham Heart Study, Boston, MA, USA | [h] Department of Neuroscience, North Dakota Medical School, Fargo, ND, USA

Correspondence: [*] Correspondence to: David J. Libon, PhD, Drexel University College of Medicine, Hahnemann University Hospital, New College Building, Mail Stop 423, 245 North 15th Street, Philadelphia, PA 19102, USA. E-mail: dlibon@drexelmed.edu.

Abstract: Background:Epidemiologic autopsy studies show mixed Alzheimer’s disease (AD)/vascular pathology in many patients. Moreover, clinical research shows that it is not uncommon for AD and vascular dementia (VaD) patients to be equally impaired on memory, executive, or other neurocognitive tests. However, this clinical heterogeneity has not been incorporated into the new diagnostic criteria for AD (Dubois et al., 2010; McKhann et al., 2011). Objective:The current research applied Latent Class Analysis (LCA) to a protocol of six neuropsychological parameters to identify phenotypic subtypes from a large group of AD/VaD participants. Follow-up analyses examined difference between groups on neuroradiological parameters and neuropsychological measures of process and errors. Methods:223 AD/VaD patients were administered a comprehensive neuropsychological protocol. Measures of whole brain and hippocampal volume were available for a portion of the sample (n = 76). Results:LCA identified four distinct groups: moderate/mixed dementia (n = 54; 24.21%), mild/mixed dementia (n = 91; 40.80%); dysexecutive (n = 49, 21.97%), and amnestic (n = 29, 13.00%). Follow-up analyses comparing the groups on neuropsychological process and error scores showed that the dysexecutive group exhibited difficulty sustaining mental set. The moderate/mixed group evidenced pronounced impairment on tests of lexical retrieval/naming along with significant amnesia. Amnestic patients also presented with gross amnesia, but showed relative sparing on other neuropsychological measures. Mild/mixed patients exhibited milder memory deficits that were intermediary between the amnestic and moderate/mixed groups. Conclusions:There are distinct neuropsychological profiles in patients independent of clinical diagnosis, suggesting that the two are not wholly separate and that this information should be integrated into new AD diagnostic paradigms.

Keywords: Alzheimer's disease, latent class analysis, mixed dementia, vascular dementia

DOI: 10.3233/JAD-132147

Journal: Journal of Alzheimer's Disease, vol. 42, no. 3, pp. 999-1014, 2014