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P4‐130: Recruiting Older African Americans for Alzheimer′s Disease Biomarker Study Involving Lumbar Punctures in Two Centers
Author(s) -
Parker Monica W.,
Howell J.Christina,
Dorbin Cornelya D.,
Mouton Charles P.,
Hu William T.
Publication year - 2016
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2016.06.2221
Subject(s) - medicine , biomarker , gerontology , distrust , african american , disease , family medicine , psychology , biochemistry , chemistry , ethnology , psychotherapist , history
Background: The focus of scientific and clinical research in Alzheimer’s disease (AD) has increasingly shifted to asymptomatic and preclinical detection. This will potentially allow prevention of mild cognitive impairment (MCI) and dementia in AD patients. We examinedwhether aHierarchical HiddenMarkov (HHM)model of wordlist memory (WLM) task performance could distinguish between normal subjects who remained normal, and normal subjects who converted to MCIADwithin 10 years.Methods:The 10-YearMayoAging Study. N 1⁄4 388 subjects diagnosed as normal at baseline. Over the study, 356 subjects remained normal (NL1⁄4>NL); 32 converted to MCI-AD (NL1⁄4>AD). An HHM model, previously developed to predict ADAS-Cog WLM task performance from ADNI and ADCS data sets, was used to predict the cognitive processing parameters (CPP) at groupand subject-levels, from the baseline AVLT WLM performance of the study participants. The HHM model had three memory states – Unlearned (U), Working Memory (WM), and Episodic Memory (EM) – 4CPPs that encoded each subject’s item responses into one of the 3 states during each study-test trial, and 5 CPPs that retrieved each subject’s recalled items from one of those states. A latent classification parameter randomly assigned each subject to either the NL1⁄4>NL orNL1⁄4>ADgroup.MarkovChainMonte Carlo sampling was used to predict each subject’s true group, and predict the 9 CPPs for each group and subject (posterior distribution). The Savage-Dickey test was used to determine any of the CPPs differed between groups. Results:Relative to the NL1⁄4>NL group, the NL1⁄4>AD group’s encoding CPPs significantly increased, while their retrieval parameters significantly decreased. Conclusions:The NL1⁄4>AD group’s increase in encoding CPPs parallels the increased medial temporal lobe metabolism seen in FDG PETand fMRI studies of normal subjects at high risk for AD. This finding supports themodel’s potential for asymptomatic AD detection.