Braak Stage is a semiquantitative measure of severity of neurofibrillary tangle (NFT) pathology. Bielschowsky silver stain was used to visualize NFTs in the frontal, temporal, parietal, entorhinal cortex, and the hippocampus. Braak stages were based upon the distribution and severity of NFT pathology:

Braak stages I and II indicate NFTs confined mainly to the entorhinal region of the brain Braak stages III and IV indicate involvement of limbic regions such as the hippocampus Braak stages V and VI indicate moderate to severe neocortical involvement.

Diagnosis includes algorithm and neuropathologist's opinion.