Participants enrolled at the Alzheimer's Disease Research Center (ADRC) at Wake Forest School of Medicine will be invited to take part in this study. The purpose of this study is to identify and measure the amount of a protein called amyloid in the brain.It is thought that the build up of amyloid may be related to the development of Alzheimer's disease.

Brain amyloid will be measured using PET with [11C]PiB. Participation will involve an initial brain scan and possibly a follow-up brain scan two years later.

The data collected in this study will help explain amyloid deposits in several groups of participants including adults with and without signs of memory impairment. The information collected will help find out who is more likely to have brain amyloid and when it increases the risk for developing memory problems. Research studies suggest that people with elevated levels of brain amyloid are at an increased risk for memory decline, but this does not mean that every person with amyloid build up will develop AD.

Inclusion Criteria:

• Enrolled in a study with the Alzheimer's Disease Research Center.

Exclusion Criteria:

-

Adults enrolled with the Alzheimer's Disease Research Center at Wake Forest School of Medicine will be invited to participate,