Graduation Year

2026

Date of Submission

12-2025

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Biology

Reader 1

Diana Williams

Reader 2

Lars Schmitz

Rights Information

2025 Mackenzie Mayfield

Abstract

Alzheimer’s disease (AD) is a growing global health crisis affecting over 55 million people worldwide, with cases expected to rise as average life span increases. With no cure for AD, research has expanded toward biological systems such as the gut microbiome and the effects of physical activity. The gut functions as the “body’s pharmacy”, while exercise influences cognition, metabolism, and gut composition. However, 1.8 billion adults fail to meet recommended activity levels, heightening their risk for cognitive decline. Current research supports a connected exercise–gut–brain axis in which physical activity reshapes gut-derived metabolite diversity to improve neural function, offering a lifestyle based pathway to reduce AD risk. This literature review evaluates recent findings across studies examining exercise, the gut microbiome, and aging/AD individually and collectively. Key mechanisms linking these systems include shifting the kynurenine pathway, reducing oxidative stress, enhancing brain-derived neurotrophic factor (BDNF) signaling, improving neural connectivity, and increasing the production of beneficial metabolites, such as butyrate. Given the rising prevalence of AD, these findings show the importance of lifestyle choices, particularly regular exercise and gut targeted strategies, as additional methods for protecting cognitive function. Together, current evidence suggests that integrating exercise interventions with targeted modulation of the gut microbiome may offer a new approach to slowing cognitive decline and reducing Alzheimer’s disease risk.

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This thesis is restricted to the Claremont Colleges current faculty, students, and staff.

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