Date of Award:

8-2024

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Psychology

Committee Chair(s)

JoAnn T. Tschanz

Committee

JoAnn T. Tschanz

Committee

Gail B. Rattinger

Committee

Mona Buhusi

Abstract

Recovery from a traumatic brain injury (TBI) is influenced by a wide array of factors including age at incidence, number, and severity as well as genetic factors, some of which exhibit sex-dependent effects. This study examines how TBI history influences rate of cognitive decline in older adults, exploring the characteristics of TBI (e.g., number, severity, and timing) as predictors and interactions of TBI history with genetic variants suspected to play a role in brain health and late-life cognitive functioning. These genes include the Apolipoprotein E (APOE) as well as brain derived neurotrophic factor (BDNF) and its receptors. This study analyzed extant data from the Cache County Study on Memory in Aging (CCSMA), a longitudinal, population-based study of over 5,000 adults, aged 65 years and older.

A history of two or more TBIs was associated with lower scores on verbal list learning. Unexpectantly, females with a history of severe TBI scored higher on a test of verbal recognition recall compared to males with no history of TBI. Furthermore, females with at least one APOE ε4 allele and two or more TBIs scored lower on global cognitive and verbal learning tasks compared to males lacking a history of TBI and the APOE ε4 allele. BDNF receptor TrkB (rs2289656) moderated the association of TBI severity on recognition tasks such that individuals with a history of severe TBI and at least one minor allele for receptor TrkB (rs2289656) scored lower than individuals lacking a history of TBI and the minor allele. Overall, this study suggests that the course of late-life cognitive decline is associated with history of TBI and the associations examining severity or number of TBI may depend on sex and genotype. Although gene modification is not a viable intervention, one may consider how to enhance BDNF activity to reduce the deleterious effects of TBI on late-life cognition. For example, physical activity and diet are lifestyle factors that promote BDNF activity and may offer a target for intervention. Future research is needed to examine this and other possible interventions to mitigate the effects of TBI on late-life cognitive decline.

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