Functional Brain Imaging of Medication Treatment Response in Mild Alzheimer's Disease Patients

This study seeks to differentiate task-related and resting brain activity patterns captured via functional magnetic resonance imaging (fMRI) and associated with two common Alzheimer's disease (AD) medications, equivalent in acetylcholinesterase inhibition effect (AChEI) but differing with respect to allosteric nicotinic receptor modulation effect. It is the primary aim of this project to gain a better understanding of the brain mechanisms involved in the attentional and executive skills improvements associated with nicotinic receptor modulation in mild AD patients. To address this question, this 12-week continuous treatment, double-blind, head-to-head dose-escalation treatment trial seeks to visualize any treatment response unique to allosteric nicotinic receptor modulation and to associate these fMRI data with standard cognitive assessment outcomes. Using in-scanner tasks shown to reliably elicit brain activity in cortical regions important to memory and attention, this treatment trial will examine both resting and task-related BOLD signal characteristics in a well-characterized sample of 36 mild AD patients after periods of low dose and high dose AD dementia treatment with either galantamine hydrobromide (AChEI + nicotinic receptor modulation) or donepezil hydrochloride (AChEI only). Both the low and high dose imaging comparisons between treatment groups will be equivalent for 35% AChEI-effect, which may allow for the isolation of BOLD signal unique to allosteric nicotinic receptor modulation in both brain at rest and task-related brain states.