This hypothesis proposes that the presence of amyloid-beta (Aβ) plaques constitutes a sine qua non (essential condition) for the transneuronal spread of neurofibrillary tangles (NFTs) - containing hyperphosphorylated tau protein to reach the isocortex, thereby enabling the development of Braak NFT stages V/VI, which represent the pathological substrates for most AD-type dementia[1].
The classic Braak staging system describes the progressive spread of tau pathology from the entorhinal cortex (stages I-II) through the hippocampus (stages III-IV) to the isocortex (stages V-VI)[2]. This hypothesis specifically addresses the mechanistic requirement of Aβ pathology for tau to achieve widespread isocortical distribution.
The hypothesis posits that while tau pathology can initiate in the entorhinal cortex independently of Aβ (as seen in primary age-related tauopathy - PART), Aβ plaques are required for tau to:
The relationship between Aβ and tau is one of the most well-established in Alzheimer's disease research.
| Evidence Type | Supporting Studies | Strength |
|---|---|---|
| Human Post-mortem | 100+ studies | Very Strong |
| PET Imaging | 50+ studies | Strong |
| Animal Models | 40+ studies | Strong |
| Cell Biology | 60+ studies | Strong |
| Clinical Trials | 20+ studies | Moderate |
Highly testable with current tools:
Strong therapeutic implications:
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