Synaptic oligomeric Tau is an early event in tau‐affected brain regions in Alzheimer’s disease.

Deposition of fibrillar forms of tau‐neurofibrillary tangles (NFT) and neuropil threads (NT) follow a progressive pattern across brain regions as reflected by Braak stages. However, oligomeric forms of tau have been proposed to precede the appearance of fibrillar forms. Synapses are the earliest structure linked to Azheimer’s Disease cognitive loss, but whether tau pathology, fibrillar or oligomeric affects early this structure in each region remains unclear. This is mainly explained by the technical limitations to study oligomeric forms of tau and the visualization of synaptic terminals. We aim to investigate the presence of oligomeric tau at synapses of human AD cases and its relation to the presence of fibrillar forms of tau in different brain regions.