The dementia of Alzheimer's disease (AD) is likely a consequence of disconnection syndromes within and between critical brain regions. As the first functional manifestations of AD may be represented by synapse loss, it is critical to exploit technologies that are sensitive to changes in structural and functional connectivity.

We are enrolling 200 individuals on the AD spectrum: 125 with dementia and 75 with prodromal AD -  25 with subjective memory complaints, and 50 with Mild Cognitive Impairment. We are enrolling 200 cognitively normal individuals from community-based studies. The sample is stratified by age, race, and sex. We complete the HCP-specified structural imaging and cognitive evaluations. fMRI and MEG include resting state and the HCP memory and motor task-based fMRI protocols. In vivo amyloid imaging is completed on all participants.

As of 10/1/2018 we have complete data from 115 participants, including 57 controls, 21 MCI, 12 with subjective complaints, and 18 with cognitive impairments but no complaints. The mean age of the sample is 66.8 years; 35% of the participants are African-American, and 61% female. African-Americans had a 14.4 times greater risk of not reporting symptoms (but having impairments) compared to those with complaints (p<.001). The control subjects had the highest cortical surface area, with the MCI and SCD participants having the lowest; the impaired individuals without complaints fell midway between the controls and MCI.

The CoBrA project will have a complete set of structural and functional brain imaging data, neuropsychological data, and amyloid imaging on 400 healthy controls and impaired individuals age 50-89 years. The high proportion of African-Americans will provide a unique platform for cross-race comparisons of risk factors and risk modifiers for the development of dementia of AD.