The primary objective of this study is to measure the concentration and the regional brain distribution of pathologic amyloid deposition using the PET tracer [C-11]PiB in participants in the UAB Alzheimer's Disease Center cohort. Assessment of interactions between race and vascular risk factors, brain amyloid levels measured with [C-11]PiB-PET, and cognitive status will be the primary outcome of this imaging study.

The primary objective of this study is to measure the concentration and the regional brain distribution of pathologic amyloid deposition using the PET tracer [C-11]PiB in participants in the UAB-ADC cohort. The amount and distribution of [C-11]PiB in the brain will be correlated to demographic, clinical, genetic, and biospecimen data acquired through the separate ongoing UAB-ADC study. Assessment of interactions between race and vascular risk factors, brain amyloid levels measured with [C-11]PiB-PET, and cognitive status will be the primary outcome of this imaging study. As a secondary aim, the investigators will assess the ability of the early flow frames from [C-11]PiB-PET and brain volumetric measurements with MRI to serve as a marker of neuronal injury and to predict cognitive status in conjunction with the amyloid-PET results.

Inclusion Criteria:

- 1. Enrollment in the UAB-ADC study under a separate IRB-approved research protocol (IRB-300000169).

2. Negative urine or serum B-hCG test within 2 days of [C-11]PiB administration in women of child bearing potential. Women who are post-menopausal with at least 1 year since last menses or documented surgical sterilization will not require pregnancy testing.

Exclusion Criteria:

1. Meets any exclusion criteria for the UAB-ADC study (IRB-300000169).
2. Inability or contraindication for undergoing MRI and/or PET imaging
3. Inability to participate in the imaging studies due to severity of dementia