Research team working on the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) Study have been provided with an extra $8 million so that they can study additional aspects of the disease.

These funds will be helpful to support additional evaluations in a subset of A4 participants. Brain PET scans are the most important ones as they are intended to measure participants' burdens of tau protein deposits.

According to Co-principal Investigator Reisa Sperling, MD, of Brigham and Women's Hospital in Boston, these scans will take help of the still-investigational AV1451 tracer in order to image tau tangles. Sperling said that one aim is to find out if there is any affect of the anti-amyloid antibody treatment on tau burdens. The researchers will study risk factors connected with degrees of baseline tau burden.

"Our natural history data in normals from Harvard Aging Brain Study suggest that amyloid is strongly correlated with tau, particularly tau spreading outside of medial temporal lobe into the cortex, and that spreading of tau is strongest predictor of memory problems", said Sperling.

The connection between amyloid and tau has not yet been understood. Sperling said that this trail will help researchers understand whether changing amyloid can really slow tau spreading. According to experts, beta-amyloid plaques and neurofibrillary tangles are the two main pathologies of Alzheimer's disease. These two are composed of hyperphosphorylated tau protein.

The new clinical studies associated with the A4 trial are going to be the biggest to date. The additional $8 million has been added by the Alzheimer's Association. The A4 trial is going to begin later this year and backed by Eli Lilly, nonprofit organizations and the National Institutes of Health.

About 1,000 enrollments are expected and they also include participants with high plaque burdens but without symptoms of cognitive decline.