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Author ORCID Identifier

https://orcid.org/0009-0000-2915-6584

Date Available

10-13-2028

Year of Publication

2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Arts and Sciences

Department/School/Program

Psychology

Faculty

Justin E. Karr

Faculty

Jessica L. Burris

Abstract

Subjective cognitive decline (SCD) is a preclinical risk factor for Alzheimer’s disease (AD) and may represent one of the earliest clinical indicators of underlying neurodegeneration. The Subjective Cognitive Decline Initiative (SCD-I) has proposed several SCD-plus features that may identify individuals at the higher risk for future cognitive decline. The current study examined whether risk of progression to MCI or dementia differed across healthy controls and four operationally defined SCD groups with stepwise accumulation of SCD-plus features. Data were obtained from 10,954 cognitively unimpaired adults aged 60 years and older enrolled in the National Alzheimer's Coordinating Center Uniform Data Set. Participants were classified into mutually exclusive healthy control or SCD groups based on four increasingly restrictive operational definitions reflecting the stepwise accumulation of SCD-plus features: subjective memory decline, perceived decline relative to peers, informant confirmation of decline, and help-seeking behavior. Cox proportional hazards regression models estimated the association between ordinal SCD group and time to incident MCI or dementia before and after adjustment for relevant covariates. Each one-category increase in ordinal SCD group was associated with a 58.9% increase in the hazard of progression to MCI or dementia (HR = 1.59, 95% CI = 1.53–1.65, p < .001). Kaplan-Meier survival curves demonstrated progressively lower MCI- and dementia-free survival with each one-category increase in SCD group (log-rank χ²(4) = 605.19, p < .001). These findings support the clinical utility of a hierarchical SCD-plus classification for identifying cognitively unimpaired older adults at progressively greater risk of MCI or dementia. Assessment of SCD-plus features during routine clinical evaluations may improve early risk stratification and inform longitudinal monitoring.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2026.447

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