One drug donanemab, which is taken as a monthly infusion for 18 months, was found to slow mental decline by 36% in phase 3 trials, US pharmaceutical giant Eli Lilly announced in May.

The drug, which is taken as a monthly infusion into the bloodstream for 18 months, was found to slow mental decline by 36% in phase 3 trials, the company announced in May.

It works by targeting and removing clusters of the protein amyloid in the brain.