MAPT and tauopathy: In summary, our findings clearly demonstrate the power of 3H-PI2620 to discriminate between AD and control cases, and emphasise that 3H-PI2620, 3H-MK6240 and 3H-RO948 could be valuable for understanding the tau heterogeneity in AD and non-AD tauopathies, through their propensity to target different tau conformations.