SYP and Alzheimer disease: Interestingly, while the injection of PSP‐tau was sufficient to induce mature neuronal and glial lesions in our previous work, we found in this study tangles (AT8‐positive), mature tangles (thioflavin‐S positive), pre‐ and post‐synaptic loss (synaptophysin and PSD‐95 expression level), and neuronal death (increased CSF total‐tau concentration) only in AD‐tau macaques co‐injected with oligomeric Aβ.