TY - JOUR
T1 - Independent contributions of neural and "higher-order" deficits to symptoms in Alzheimer's disease
T2 - A latent variable modeling approach
AU - Tractenberg, Rochelle E.
AU - Aisen, Paul S.
AU - Weiner, Myron F.
AU - Cummings, Jeffrey L.
AU - Hancock, Gregory R.
N1 - Funding Information:
Supported by a Research Starters Grant in Health Outcomes from the Pharmaceutical Researchers and Manufacturers Association of America (PhRMA) Foundation to RET and a Mentored Research Scientist Award from NIA to RET, K01AG027172. The data were collected by the Alzheimer’s Disease Cooperative Study under NIA Grant U01 AG10483.
PY - 2006/10
Y1 - 2006/10
N2 - Background: Analytic models of Alzheimer's disease (AD) tend to focus on one type of symptom and assume implicitly that no measurement error is present. These tendencies render changes in symptom domains difficult to model mathematically, although latent variable methods can accommodate both multiple symptom domains and error. This study formulated and compared underlying (latent) factor structures representing previously reported dependence and independence of symptoms of cognitive decline, functional impairment, and behavioral disturbance in AD. Methods: In confirmatory factor analyses of data from 2 cohorts of AD patients, 2 levels of latent variables were conceptualized. One general neurologic factor represented disease, and symptom factors represented cognition, function, and behavior. Two "null" models had either a single factor or 3 symptom factors. Two 2-level models treated the general factor as underlying both the observed variables and the symptom factors or treated the symptom factors as explaining variability in the observed variables after taking the general factor into account ("residualized"). Results/Conclusions: The residualized model fit the data in both cohorts significantly better than the other models, and relations in this model between some observed and latent variables were different across cohorts. Neither cohort supported a single factor model; both cohorts independently supported a residualized model that may permit differentiation of symptom- from disease-modifying effects of treatment.
AB - Background: Analytic models of Alzheimer's disease (AD) tend to focus on one type of symptom and assume implicitly that no measurement error is present. These tendencies render changes in symptom domains difficult to model mathematically, although latent variable methods can accommodate both multiple symptom domains and error. This study formulated and compared underlying (latent) factor structures representing previously reported dependence and independence of symptoms of cognitive decline, functional impairment, and behavioral disturbance in AD. Methods: In confirmatory factor analyses of data from 2 cohorts of AD patients, 2 levels of latent variables were conceptualized. One general neurologic factor represented disease, and symptom factors represented cognition, function, and behavior. Two "null" models had either a single factor or 3 symptom factors. Two 2-level models treated the general factor as underlying both the observed variables and the symptom factors or treated the symptom factors as explaining variability in the observed variables after taking the general factor into account ("residualized"). Results/Conclusions: The residualized model fit the data in both cohorts significantly better than the other models, and relations in this model between some observed and latent variables were different across cohorts. Neither cohort supported a single factor model; both cohorts independently supported a residualized model that may permit differentiation of symptom- from disease-modifying effects of treatment.
KW - Activities of daily living
KW - Behavior disorders
KW - Cognition disorders
KW - Data interpretation
KW - Factor analysis
KW - Geriatric assessment
KW - Statistical
KW - Statistics
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U2 - 10.1016/j.jalz.2006.08.001
DO - 10.1016/j.jalz.2006.08.001
M3 - Article
C2 - 19595904
AN - SCOPUS:33749526850
SN - 1552-5260
VL - 2
SP - 303
EP - 313
JO - Alzheimer's and Dementia
JF - Alzheimer's and Dementia
IS - 4
ER -