Metformin in Alzheimer's Dementia Prevention

MAP will be a multi-center phase 2/3 1:1 randomized controlled trial (RCT) of long-acting metformin (reduced mass Glucophage XR) vs. matching placebo in 326 men and women with early and late aMCI, without diabetes, not treated with metformin, overweight or obese, aged 55 years to 90 years. The RCT will last 18 months and have 4 visits: baseline, 6-months, 12-months, and 18-months. The RCT will be preceded by a screening phase followed by randomization and a titration period in which drug/placebo will be titrated from 500 mg a day (one tablet) to 2,000 mg a day (4 tablets), in increments of 500 mg (one tablet) every 10 days. Participants will remain in the RCT on the tolerated dose, and included in analyses on an intent to treat basis. We expect the attrition rate to be 10%/year. Neuropsychological battery, clinical interviews, physical exam, and phlebotomy will be conducted at baseline and every 6 months. Brain MRI will be conducted in approximately half of the participants (186) twice, at baseline, and after the last study visit at month 18. We will also conduct brain amyloid Positron Emission Tomography (PET) using 18F-Florbetaben, and tau PET using 18F-MK6240 in half of the participants at baseline and end of the RCT. The primary clinical outcome of the study will be changes in the Free and Cued Selective Reminding Test. The secondary endpoints are 1) changes in global cognitive performance, measured with the Alzheimer's Disease Cooperative Study Preclinical Alzheimer Cognitive Composite (ADCS-PACC); 2) changes in neurodegeneration, ascertained as cortical thickness in areas affected by AD on brain MRI; 3) changes in cerebrovascular disease, ascertained as white matter hyperintensities (WMH) volume on brain MRI; 4) Changes in whole brain amyloid ß (Aß) SUVR and in incident amyloid positivity; 5) Changes in tau SUVR in a composite brain region comprising medial and inferolateral temporal cortex; 6) Changes in plasma AD biomarkers. The data coordinating center and Imaging Core is located at John Hopkins University. The PET coordinating center is located at UC-Berkeley. The Clinical Coordinating and Monitoring Center and the central laboratory will be located at Columbia. The Research pharmacy function will be shared by the University of Rochester, which will dispense randomization kits, and the University of Iowa, which will receive bulk metformin and identical matching placebo from EMD Serono.