Hypothesis: Modulation of microglial phenotype in Alzheimer's disease drives neurodegeneration

Area of Science:

• Neuroscience
• Pathology
• Neurology

Background:

• The precise pathophysiology of Alzheimer's disease (AD) is not fully understood.
• The prevailing amyloid hypothesis explains some aspects of AD but has limitations.
• Unexplained temporal and spatial features of AD progression require further investigation.

Purpose of the Study:

• To propose a novel hypothesis for Alzheimer's disease pathophysiology.
• To integrate early pathological events and downstream consequences in AD.
• To elucidate the roles of amyloid deposition, blood-brain barrier permeability, and microglial activation in AD.

Main Methods:

• This article presents a hypothesis based on existing evidence.
• It synthesizes findings related to amyloid pathology and blood-brain barrier function.
• It examines the downstream effects on microglial activation, synaptic function, and glutamate signaling.

Main Results:

• Amyloid deposition and increased blood-brain barrier permeability are proposed as independent early events in AD.
• These events together induce a specific microglial activation phenotype.
• Downstream consequences include synapse phagocytosis and persistent N-methyl-D-aspartate receptor signaling.

Conclusions:

• The proposed hypothesis offers a framework for understanding AD pathophysiology.
• It integrates early events with neurodegeneration and tau pathology.
• This model aims to explain previously unexplained features of Alzheimer's disease progression.