Competing interests: The BMJ has judged that there are no disqualifying financial ties to commercial companies. The authors declare the following other interests: Dr Kantarci was involved in an unpaid educational activity on Alzheimer’s disease for Biogen Inc. and is the PI on a study of a PET imaging ligand for Alzheimer's disease, to which Eli Lilly and Avid Radiopharmaceuticals, donated supplies. She is funded by the National Institutes of Health (NIH) and Alzheimer’s Drug Discovery Foundation (ADDF). Dr Manson reports no relevant disclosures.