Random change point model for joint modeling of cognitive decline and dementia |
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Authors: | Jacqmin-Gadda Hélène Commenges Daniel Dartigues Jean-François |
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Institution: | Institut National de la Santé et de la Recherche Médicale, Equipe de biostatistique E0338, Université Victor Segalen Bordeaux 2, Bordeaux, France. |
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Abstract: | We propose a joint model for cognitive decline and risk of dementia to describe the pre-diagnosis phase of dementia. We aim to estimate the time when the cognitive evolution of subjects in the pre-dementia phase becomes distinguishable from normal evolution and to study whether the shape of cognitive decline depends on educational level. The model combines a piecewise polynomial mixed model with a random change point for the evolution of the cognitive test and a log-normal model depending on the random change point for the time to dementia. Parameters are estimated by maximum likelihood using a Newton-Raphson-like algorithm. The expected cognitive evolution given age to dementia is then derived and the marginal distribution of dementia is estimated to check the log-normal assumption. |
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Keywords: | Joint model Longitudinal data Mixed model Random effects |
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