Before Covid, dementia was the biggest killer in the UK and Alzheimer’s disease is the most common type. A controversial new drug for Alzheimer’s, aducanumab, is the first in nearly 20 years to be approved in the US, which will trigger pressure to make it available worldwide. The Guardian’s health editor, Sarah Bosley, talks Shivani Dave through the mixed evidence of its efficacy. Help support our independent journalism at theguardian.com/sciencepod