The 16th International AD/PD meeting was also the first hybrid version, drawing some 3,360 participants online, or in person in Barcelona, Spain. Scientists outlined Roche’s new Phase 3 secondary prevention trial of gantenerumab for the first time. Attendees also heard updates on Aduhelm, lecanemab, and α-synuclein immunotherapy. On the basic science front, tau emerged as an instigator of interferon responses, while presentations on postmortem single-nuclei data showed how collectives of cell subtypes, and their cross talk, wax and wane together with age and with AD pathology.