Fig. 4.

Preserved DaT availability relative to tau burden suggests concept of a motor reserve in patients with 4RT. A Residuals of the linear regression between the tau-PET principal component 1 (tau-PET PC1) and the DaT-SPECT principal component (DaT-SPECT PC) positive (green) and negative (red) were obtained as an index of preserved DaT availability despite tau burden. Preserved DaT availability was associated with lower disease severity in the PSP rating scale (right panel). Only patients with PSP rating scale scores are depicted. B Exemplary patients with 4R-tauopathies showing high tau burden, preserved DaT availability and mild clinical severity (upper row, 73y, female, PSP-CBS, PSP rating scale: 26) as well as moderate tau burden, strongly decreased DaT availability and severe clinical deterioration (lower row, 79y, female, PSP-CBS, PSP rating scale: 49). Axial slices show individual tau-PET z-scores on a standard MRI-template in contrast against healthy controls and individual DaT SPECT ratio images