Dr. Irina Skylar-Scott

BIIB080

for Alzheimer's Disease

In this study, researchers will learn more about a study drug called BIIB080. The study will focus on participants with mild cognitive impairment or mild dementia due to AD. The main question researchers are trying to answer is if BIIB080 can slow the worsening of AD more than placebo. It will focus on what dose of BIIB080 slows worsening of AD the most. To help answer this question, researchers will use the Clinical Dementia Rating-Sum of Boxes, also known as the CDR-SB. Clinicians use the CDR-SB to measure several categories of dementia symptoms. The results for each category are added together for a total score. Lower scores are better. Researchers will also learn more about the safety of BIIB080. A description of how the study will be done is given below. Participants will receive either a low dose or high dose of BIIB080 or a placebo as an injection into the fluid around the spinal cord. A placebo looks like the study drug but contains no real medicine. The fluid around the spinal cord is called the cerebrospinal fluid. Participants will be in the study for 105 weeks, or a little over 2 years. This includes the screening and follow-up periods. Participants will be given BIIB080 or placebo once every 12 weeks for a total of 72 weeks. Participants can continue to take certain medications for AD. Participants must be on the same dose of medication for at least 8 weeks before the screening period. After the screening period, most participants will visit the clinic every 6 weeks.