Memory loss can develop for a number of reasons, but before the age of 65 it is rarely due to Alzheimer’s disease (AD) — in fact, it is rare to have symptoms of AD until after age 75. Although Alzheimer’s disease remains the most common cause of dementia in the US (there are many other causes of dementia), our science is improving. We are now aware that people can have changes in their brain upwards of 10-20 years before significant symptoms of AD develop. For the first time ever, research studies are allowing us to help people with these changes before they get symptoms, in hopes of preventing the disease from developing. For that reason, we are doing more testing than ever before.