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Advisory Committee Chair

Virginia B Wadley

Advisory Committee Members

Karlene K Ball

Michael G Crowe

David E Vance

Document Type

Dissertation

Date of Award

2011

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Mild cognitive impairment (MCI) is 2 to 5 times more common than dementia and can be a predisposing marker for the development of dementia. African Americans are reported to be at an increased risk for developing MCI when compared to Caucasians. The purpose of the present study was to examine reasons for racial disparity in rates of MCI classification and, in particular, whether preservation of functional abilities over time occurs among African Americans so classified, suggesting possible misclassification. Level and quality of education and prevalence of vascular disease were examined as mediators of the racial disparity in MCI classification. Previously established criteria for MCI classification yielded 431 participants with possible MCI at enrollment in the ACTIVE study. The remaining 2,326 participants comprised the cognitively normal reference group. After adjusting the initial logistic regression model for potential confounders, African Americans were more than four times as likely to be classified with psychometrically defined MCI as the Caucasians in this sample. Adjusting the model to include educational attainment and quality reduced the likelihood of MCI classification for African Americans by more than half, from an OR of 4.42 to an OR of 2.04. A series of random effects linear regression models were used to examine longitudinal trajectories of objective (TIADL and OTDL) measures and subjective (ADL and IADL) measures of functional ability over the course of two years in order to determine if MCI x Race interactions would reveal that African Americans were at a greater risk for MCI misclassification. Though no MCI x Race interactions were observed on the objective measures of functional ability; African Americans with MCI reported lower levels of IADL difficulty than Caucasians with MCI from baseline to Year 2 as well as lower levels than Caucasians without MCI from baseline to Year 1. These finding supports our hypothesis that African Americans are at risk for possible MCI misclassification.

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