A Pilot Clinical Trial of Exendin-4 in Alzheimer's Disease

Background: Exendin-4 (or Exenatide) is a medication currently used to treat diabetes that has shown promising results in animal and cellular models of Alzheimer's disease. It is possible that Exendin-4 may be a treatment for Alzheimer's disease, which involves the gradual deterioration and death of neurons. Researchers are interested in studying the safety and comparing the effects of Exendin-4 with placebo on cognitive performance, clinical progression of dementia, various chemicals measured in blood and cerebrospinal fluid, and brain MRI, in individuals with early-stage Alzheimer's disease or mild cognitive impairment. Objectives: To determine the safety and tolerability of twice daily administration of Exendin-4, as well as to acquire preliminary evidence for effects on cognitive performance, clinical progression of dementia, various chemicals measured in blood and cerebrospinal fluid, and brain MRI, in individuals with early-stage Alzheimer's disease or mild cognitive impairment. Eligibility: Individuals at least 60 years of age who have objective evidence of early-stage Alzheimer's disease or mild cognitive impairment in screening testing. Design: * Participants will be screened. * Following the telephone screening, two in-person screening visits to determine eligibility. * The screening visit will involve a medical history and neurological examination, tests of memory and cognition, a lumbar puncture, collection of blood and saliva samples, and brain Magnetic Resonance Imagine (MRI) studies. Participants will be required to appoint a Durable Power of Attorney for research and medical care during this protocol. * Eligible participants will be divided into two groups (double-blind randomization). One group will receive Exendin-4 SC twice daily, and the other will receive a placebo. Participants will keep a medication diary and will be scheduled for additional study visits 1 and 2 weeks after the start of the treatment. * Participants will have regular fo