Using western blots, we have compared the analysis of brain homogenates from Alzheimer patients (A1 to A6) versus aged-matched controls (C1 to C6). The tissue is sampled in the parietal cortex. We have specifically revealed pathological tau proteins, using AD2, a phospho-dependent tau antibody.

Results: Pathological tau proteins are highly concentrated in Alzheimer brain extracts, but not in the normal brain tissue. It shows that aggregated tau proteins are excellent markers of Alzheimer's disease degenerating process.

Furthermore, the approach is quantitative. For exemple, despite the fact we have loaded the gel with the same amount of brain homogenate (1+10 volume SDS), patient 2 contains more pathological tau. In fact, this higher amounts fit well with neuropathological findings (more tangles) and clinical data (young patient, rapid evolution).

Tau pathology has different biochemical signatures that are disease-specific (see the code-bar of tauopathy).

Tau also spreads in the CNS along neuron-to-neuron connections. The pathway of spreadin is different according to the pathology and to the first vulnerable area affected by tauopathy:

The biochemical pathway of tau spreading in aging and Alzheimer's disease

The biochemical pathway is PSP