Date of Award

January 2012

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Becca Levy

Second Advisor

Rafael Perez-Escamilla

Abstract

Introduction

Diabetes is a proposed cause of dementia and age-related cognitive decline. While the effects of hyperglycemia, insulin resistance, and hyperinsulinemia are well-known, scholarship tends to neglect distinct but related pathologies, such as chronic stress. The purpose of this study is to evaluate whether a common proxy- mid-life involuntary job loss- is associated with reduced cognitive function among a cohort of diabetics. A second objective was to determine if age of diabetes onset moderates this relationship.

Methods

This cross-sectional study gathered diabetes data from the 2003 Health and Retirement Study (HRS) Mail Survey on Diabetes, while measures of cognitive function (HRS-Cog) and socio-demographic variables were assessed in the 2002 and 2004 HRS waves. Multivariate regression was used to analyze the impact of job loss on cognitive function between 1992 and 2002 among 153 job losers and keepers with complete data for employment history, the 35-point HRS-Cog, age of diagnosis, and glycemic control (HbA1c).

Results

Job losers scored 1.52 points (-3.28-0.24, p<0.09) below keepers in the best fit model, adjusted for age of onset (<=55, >55) HbA1c quartiles, sex, education, hypertension, and retinopathy. Age of onset did not moderate the association between job loss and cognitive function (β = -2.15, CI: -3.89- -0.40; p=0.016); sex, however, was solely responsible for the reversed, non-significant association in model two (β = -0.37, CI: -2.17-1.43; p=0.687). Adjustment for all covariates eliminated the significance of the job loss differential, as well as the effect of onset. Retinopathy, education, and sex remained significant across all adjustments. Finally, the significance of job loss and onset was independent of each other and their magnitude comparable across most adjustments.

Discussion

The relationship of involuntary mid-life job loss to cognitive function may reflect the myriad effects of chronic stress. Even after controlling for well-established predictors of cognitive decline, the impact of job loss was comparable to the timing of diagnosis. Because the significance of these two variables, as well as retinopathy, remained when modeled simultaneously, the effects of stress may involve unique and systemic pathways. Furthermore, despite strong moderating effects from gender, the magnitude of the coefficient on job loss and the relatively young cohort are evidence for the hypothesis of premature aging. This study demonstrates that appropriate interventions may benefit high-risk groups such as those with type II diabetes and that cortisol could be a viable co-factor related to cognitive function.

Comments

This is an Open Access Thesis.

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