AD is a progressive disease, such that it starts in the entorhinal cortex and hippocampus, and then slowly spreads to other parts of the brain. AD’s first clinical stage is identified as mild cognitive impairment (MCI). The amnestic subtype of MCI is strongly associated with AD and some studies estimate that approximately 80% of people with amnestic MCI go on to develop Alzheimer's disease within 6 years. According to the Mayo Clinic, 15-20% of MCI patients convert to Alzheimer's disease each year while the conversion rate for the general population is 1-2%.