Patent ID: 7335652

Claim:
A method for determining the Braak stage of neurofibrillary degeneration associated with a tauopathy in a subject believed to suffer from the disease, which method comprises the steps of: (i) introducing into the subject a ligand that labels aggregated paired helical filament (PHF) tau protein, wherein the ligand is capable of crossing the blood brain barrier, and wherein the ligand is conjugated, chelated, or otherwise associated, with a detectable chemical group, (ii) determining the presence and\or amount of ligand bound to extracellular aggregated PHF tau in the medial temporal lobe of the brain of the subject, and (iii) correlating the result of the determination made in (ii) with the extent of neurofibrillary degeneration in the subject to determine the Braak stage, wherein the method is used for detection of early Braak stages before appearance of clinical symptoms, pre-mortem diagnosis and discrimination of advanced Braak staging, and wherein the ligand is a compound of one of the following formulae: wherein: each of R 1 , R 3 , R 4 , R 6 , R 7 and R 9 is independently hydrogen, halogen, hydroxy, carboxy, substituted or unsubstituted alkyl, haloalkyl, or alkoxy; R 5 is independently hydrogen, hydroxy, carboxy, substituted or unsubstituted alkyl, haloalkyl, or alkoxy; R 10 and R 11 are independently selected from hydrogen, hydroxy, carboxy, substituted or unsubstituted alkyl, haloalkyl, or alkoxy; or a pharmaceutically acceptable salt thereof.