News from Science reports mixed phase 2 results for diranersen, Biogen’s drug designed to lower the body’s production of tau. The trial involved more than 400 patients with early-stage Alzheimer’s. On its main cognition measure, participants receiving the drug saw as much as a 26% slowing of decline—about on par with effects seen in earlier trials of approved antiamyloid drugs. But the lowest dose produced the greatest benefit, so the trial missed its primary endpoint targeting a dose-dependent effect. Some patients in the higher-dose groups also experienced a potentially worrisome “confusional state” lasting up to a week after the drug was administered.