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Change point models allow for estimation of the time at which cognitive decline accelerates in preclinical dementia

Background. Dementia: Decline in memory plus at least one additional cognitive domain.Does accelerated decline in memory precede diagnosis?Accelerated decline in other cognitive domains?If so, WHEN?Hall et al, Statistics in Medicine, May 2000.Hall et al, Statistics in Medicine, December 2001

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Change point models allow for estimation of the time at which cognitive decline accelerates in preclinical dementia

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    1. Change point models allow for estimation of the time at which cognitive decline accelerates in preclinical dementia   Charles B. Hall (Albert Einstein College of Medicine) Richard B. Lipton, Herman Buschke, Mindy J. Katz (Albert Einstein College of Medicine) Martin J. Sliwinski (Syracuse University) Jun Ying, Lynn Kuo (University of Connecticut)  

    2. Background Dementia: Decline in memory plus at least one additional cognitive domain. Does accelerated decline in memory precede diagnosis? Accelerated decline in other cognitive domains? If so, WHEN? Hall et al, Statistics in Medicine, May 2000. Hall et al, Statistics in Medicine, December 2001.

    3. Methods Mature cohort with extensive follow up Examine natural history relative to time of dementia diagnosis Inflection point models to determine when cognitive decline accelerates:

    4. Data Used -- Bronx Aging Study 488 initially healthy community dwelling individuals Blessed > 8 + Functional Decline for time of dementia diagnosis Subtypes by case conference Analyzed AD cases plus “mixed” Examined cognition as function of age, time before diagnosis Buschke Selective Reminding (memory) Block Design and Digit Symbol from WAIS (speed tasks)

    5. Selective Reminding

    6. WAIS Block Design, Digit Symbol

    7. Fitting the Change Point Model Try a range of change points, computing goodness of fit. Select the one that fits the best. Easy in SAS, S-Plus. Statistical theory: profile likelihood. Confidence intervals as well!

    8. Comparison of Memory with Speeded Tasks

    9. Comparison of Memory with Speeded Tasks

    10. Do all subjects have the same change point? Bayesian methods available to fit:

    11. Conclusions Profile likelihood easy to implement for estimation of inflection points in growth curve models. Bayesian method available when necessary. Cognitive decline accelerates prior to AD onset for Selective Reminding, Block Design, Digit Symbol. Onset of accelerated decline varies across cognitive domains. Accelerated decline in memory precedes that in speeded tasks – first rigorous demonstration.

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