A 74-year-old woman is brought in by her daughter for gradua…

A 74-yeаr-оld wоmаn is brоught in by her dаughter for gradually worsening memory over the last 18 months. She frequently misplaces objects, repeats questions, and recently got lost driving in her own neighborhood. MoCA (Montreal Cognitive Assessment) score for memory is significantly decreased at 19/30, and MRI shows hippocampal atrophy. Labs reveal normal TSH, B12, and electrolytes. What is the most likely underlying pathophysiologic process associated with this clinical presentation?