Is executive function impairment an Alzheimer’s disease variant in African Americans or a separate and distinct dementia phenotype? Open Access

Garrett, Stephanie (Spring 2020)

Permanent URL: https://etd.library.emory.edu/concern/etds/nc580n74r?locale=en
Published

Abstract

Problem/Relevance:  African Americans (AA) are at increased risk of developing Alzheimer’s disease (AD) yet are less likely to be diagnosed. It is unclear if this is due to health seeking practices, cultural views and misconceptions regarding cognitive decline and dementia, or more clinical reasons. Waiting for memory impairment, a key requirement in the clinical diagnosis of dementia, may be too late for early detection of cognitive impairment in AA. Rather, we postulate that executive function may be a better domain to assess as it is vulnerable to the effects of hypertension, a highly prevalent condition in AA. Furthermore, we hypothesize that executive function impairment is an AD nonamnestic variant associated with AD cerebral spinal fluid (CSF) biomarkers.

Design/Analysis:  The current investigation is a cross-sectional analysis of data from a cohort study, Brain Stress Hypertension and Aging Research Program (BSHARP), a study that over-sampled AA to permit studies regarding racial disparities.  Statistical tests of comparison between AA and Whites were completed to assess for group differences, and regression analyses conducted to assess potential associations between executive function impairment and AD CSF biomarkers.

Findings:  Baseline data from 366 participants are reported here. AA (41.8% of the total sample) were younger (mean age 63.2 ± 6.7) than Whites (67.4 ± 8.2), possessed less formal education, and had higher proportions of hypertension, and obesity.  Executive function impairment, defined as difficulty in higher-order cognitive skills involved in coordination and regulation, occurred in 20% of the sample- 26% of AA and 15% of Whites. Risk factors associated with impaired executive function were AA race (OR= 2.46 [1.11, 5.50]), and 10-year increase in age (OR= 1.80 [1.04, 3.10]). We found no association between impaired executive function and AD CSF biomarkers (OR 1.0 AB1-42, OR 0.99 Tau, OR 0.96 pTau), when analyzed by cognitive status, when adjusted for age, sex, education in years, and family history of AD, or when race interaction was included. There was an association between Tau to amyloid ratio, or TAR (OR 1.16 SE 1.64) and impaired executive function but this OR significantly increased to 7.45 for the adjusted analysis, likely indicating lack of power.  

Table of Contents

INTRODUCTION …………………………………………………………………... 1

BACKGROUND ……………………………………………………………………... 3

METHODS …………………………………………………………………………… 5

RESULTS ……………………………………………………………………………..10

DISCUSSION / CONCLUSIONS ……………………………………………......13

REFERENCES ……………………………………………………………………… 15

TABLE 1. Baseline Sample Characteristics of Study Participants.......…17

Figure 1. Prevalence of Executive Function Impairment Overall ......... 18

Table 2. Multivariable analysis of risk factors …………………………..... 19

Table 3. Odds of executive function impairment ……………………….... 20

Table 4. Odds of executive function impairment with race …….…....... 21

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