Ferric cycle activity and Alzheimer disease

Area of Science:

• Neuroscience
• Biochemistry
• Pathology

Background:

• Elevated plasma homocysteine is a known risk factor for Alzheimer disease (AD).
• The exact mechanisms linking homocysteine to AD pathogenesis remain largely unknown.
• Iron dysregulation and oxidative stress are implicated in AD.

Purpose of the Study:

• To propose a novel hypothesis on the role of homocysteine in AD development.
• To elucidate the mechanisms involving iron dysregulation, oxidative stress, and heme deficiency in AD.
• To present a model for AD development and progression based on the ferric cycle.

Main Methods:

• Review and synthesis of existing literature on homocysteine, iron metabolism, oxidative stress, and AD pathology.
• Development of a theoretical model (the ferric cycle) linking these factors.
• Correlation of the proposed model with established pathological hallmarks of AD.

Main Results:

• A novel hypothesis, the ferric cycle, is proposed, involving homocysteine, iron dysregulation, and oxidative stress.
• The ferric cycle may lead to critical heme deficiency in neurons.
• This model explains various AD pathologies, including mitochondrial dysfunction, impaired metabolism, and altered iron homeostasis markers.

Conclusions:

• The ferric cycle offers a unifying explanation for AD development and progression.
• It provides insight into the differences between sporadic AD and normal aging.
• The model suggests common end-stage mechanisms for both familial and sporadic AD, despite potentially different etiologies.