Just a few months after the announcement of lecanemab as a drug for slowing Alzheimer’s progression, a second new drug has been announced by pharmaceutical firm Eli Lilly. Called donanemab, it is also a monoclonal antibody drug for removing amyloid protein that builds up in the brain as Alzheimer’s disease progresses. In people with mild Alzheimer’s disease and mild cognitive impairment, donanemab slowed memory and thinking decline by 35% over 18 months, comparing favourably with lecanemab where the figure was 27%. According to Eli Lilly, donanemab resulted in 40% less decline in abilities to perform activities of daily living and nearly half of participants (47%) showed no decline at all on a key measure of Alzheimer’s severity after one year. But there were serious side effects in some participants which will need to be understood before the drug can be put on the market. Anne White, Eli Lilly’s executive vice president, said the drug could be a “significant step forward” for people with early Alzheimer’s, allowing them “to continue to participate in activities that are meaningful to them.”