Enhancing Memory in Mild Cognitive Impairment and Early Stage Alzheimer's Disease

The investigators have developed a low-risk transcranial Electrical Stimulation (tES) treatment that has improved learning and performance in young adults up to nearly 4 times when compared with a sham control. This randomized pilot trial will determine if this same tES protocol improves memory in older adults (50-90 years old) who are healthy, and separately in older adults with mild cognitive impairment (MCI) or early stage Alzheimer\'s disease (AD). TES will be applied to the right temple and left arm for up to 40 minutes. MRI images, along with other measures, may be obtained before and after tES. If effective, this intervention may help to improve the quality of life for AD patients and their families.