Random change point model for joint modeling of cognitive decline and dementia.
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.
Institut National de la Santé et de la Recherche Médicale, Equipe de biostatistique E0338, Université Victor Segalen Bordeaux 2, Bordeaux, France.
Hélène
H
Jacqmin-Gadda
Daniel
D
Commenges
Jean-François
JF
Dartigues
D000465:Algorithms; D003072:Cognition Disorders / Q000175:diagnosis*; D003704:Dementia / Q000175:diagnosis*; D018450:Disease Progression; D004522:Educational Status; D006801:Humans; D016013:Likelihood Functions; D008954:Models, Biological; D012306:Risk