In vivo coupling of dendritic complexity with presynaptic density in primary tauopathies.

Abstract Understanding the cellular underpinnings of neurodegeneration remains a challenge; loss of synapses and dendritic arborisation are characteristic and can be quantified in vivo, with [11C]UCB-J PET and MRI-based Orientation Dispersion Imaging (ODI), respectively. We aimed to assess how both measures are correlated, in 4R-tauopathies of progressive supranuclear palsy – Richardson's Syndrome (PSP-RS; n = 22) and amyloid-negative (determined by [11C]PiB PET) Corticobasal Degeneration (CBD; n =14), as neurodegenerative disease models, in this proof-of-concept study. Compared to controls (n = 27), PSP-RS and CBD patients had widespread reductions in cortical ODI, and [11C]UCB-J non-displaceable binding potential (BPND) in excess of atrophy. In PSP-RS and CBD separately, regional cortical ODI was significantly associated with [11C]UCB-J BPND in disease-associated regions (p