Discriminant Validity and the Prevalence of Depression Among Individuals with Parkinson’s Disease Open Access

Littrell, Kevin (Spring 2018)

Permanent URL: https://etd.library.emory.edu/concern/etds/707957685?locale=en


Background: Parkinson’s Disease (PD) is currently the most prevalent movement disorder and the second-most common neurodegenerative disorder in the developed world. One area that is particularly important to achieving modern, affordable PD care is establishing the validity of psychometric tools when used among the PD population.

Methods: The observed odds ratio between PD and depression was estimated using the traditionally defined criteria for the Beck Depression Inventory - II, a score of ≥ 14 signifying depression. Then a specificity analysis and a confirmatory factor analysis, with the Apathy Scale, were conducted to investigate the influence of misclassification bias in the prevalence estimate.Results: The observed OR for the association between PD and depression is 3.15 (0.61–16.22). While not all specificity combinations provided realistic bias-adjusted estimate, in general, as the specificity decreases, the association between depression and PD is more likely to be an overestimate. In the factors that met the inclusion criteria, the control group fit a six-factor model: general depression (factor 1), somatic depression (factor 2), cognitive depression (factor 3), dysphoria (factor 4), behavioral apathy (factor 5), cognitive apathy (factor 6). The PD case group fit a five-factor model: general depression (factor 1), frustration (factor 2), somatic changes (factor 3), dysphoria (factor 5), and self-perception (factor 6). Conclusion: Support was found that depression is more common among individuals with PD than in other old adults. However, the study of this association is complicated by the influence of apathy and PD symptoms. In addition, when arguing that the overlapping symptoms between PD and depression causes the specificity of common depression screening tools to decrease, depression can be overestimated. However, the extent to which this is true depends on the validity of the psychometric tool used to measure depression.

Table of Contents


About this Master's Thesis

Rights statement
  • Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.
Subfield / Discipline
  • English
Research Field
Committee Chair / Thesis Advisor
Committee Members
Partnering Agencies
Last modified

Primary PDF

Supplemental Files