Publication Date

Fall 2025

Degree Type

Thesis

Degree Name

Master of Arts (MA)

Department

Psychology

Advisor

Valerie Carr; Christina Tzeng; Gregory Feist

Abstract

Alzheimer’s disease (AD) is the most common form of dementia and is characterized by episodic memory impairment. Numerous functional magnetic resonance imaging (fMRI) studies have examined brain activity differences between individuals with AD and age-matched controls during memory encoding. However, small sample sizes and methodological variability across studies have limited the ability to draw meaningful conclusions regarding brain activity underlying encoding impairments. We conducted a meta-analysis to identify consistent patterns of hyperactivity and hypoactivity in AD during episodic memory encoding. Using PubMed to identify studies that met our inclusion criteria, 1,002 studies were screened; ultimately, seven studies were included in the hyperactivity meta-analysis and ten in the hypoactivity meta-analysis. We next extracted the spatial coordinates of brain areas showing significant differences in encoding activity between AD and control groups from each study, and performed coordinate-based meta-analyses using GingerALE. No significant clusters of hyper- or hypoactivity were found using the planned statistical approach. However, an exploratory analysis using a more liberal statistical approach revealed bilateral hyperactivity in the precuneus in the AD group. The precuneus is a highly interconnected region thought to be particularly vulnerable to pathophysiological processes, including abnormal functional activity. More comprehensive, well-powered studies are needed to replicate this finding and further our understanding of neural mechanisms underlying memory dysfunction in AD.

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