Small-diffusible aggregates, plaques, tangles, and dynamic equilibria: Untangling Alzheimer's disease

Area of Science:

• Neuroscience
• Neuropathology
• Alzheimer's Disease Research

Background:

• Alzheimer's disease (AD) is characterized by beta-amyloid plaques and tau tangles.
• The exact role of these aggregates in AD pathophysiology remains unclear.
• Smaller, soluble aggregates of beta-amyloid and tau may be more toxic than large, insoluble plaques and tangles.

Purpose of the Study:

• To hypothesize that the formation of small and large beta-amyloid and tau aggregates is a non-linear process.
• To explore the differential mechanisms regulating the formation of soluble versus insoluble aggregates in AD.

Main Methods:

• Synthesized recent findings from the authors' group and other key research.
• Integrated existing knowledge on aggregate formation and clearance in Alzheimer's disease.

Main Results:

• Small-diffusible aggregate formation of beta-amyloid and tau is a passive, thermodynamically regulated process.
• Large-insoluble aggregate formation (plaques and tangles) is an active process modulated by microglia and neurons.
• Active formation of plaques and tangles may serve as a protective mechanism against smaller, more toxic aggregates.

Conclusions:

• The imbalance between the production and clearance of beta-amyloid and tau aggregates may drive AD pathology.
• Plaque and tangle formation might represent an active, albeit potentially insufficient, attempt by the brain to restore homeostatic equilibrium.
• Understanding the distinct formation pathways of soluble and insoluble aggregates is crucial for developing effective Alzheimer's disease therapeutics.