In 1991, Professor Heiko Braak of Germany and his wife reported a tool that directly measured the development of Alzheimer’s related pathology in patients. Braak graded the presence, distribution and density of tau tangles in the brain and defined six distinct stages of Alzheimer’s progression (Braak stages).
The TauRx research team built on the findings of the Braaks and demonstrated, in a clinical setting, a strong correlation between the degree of tau protein neurofibrillary pathology in the brain as measured using Braak staging, the amount of aggregated tau in pre-tangle brain regions and the degree of cognitive incapacitation as measured by scores on the mini mental state exam (MMSE). The Braak neuropathological staging system for Alzheimer’s disease provides a way to directly measure the relationship between tau aggregate formation and cognitive decline [loss of memory].
Braak and Braak. (1991) Neuropathological stageing of Alzheimer-related changes. Acta Neuropathol 82:239-259.