A swift and accurate diagnosis of Alzheimer's has a huge impact on access to treatments and eligibility for research trials, plus much-needed support and information services. Yet this diagnosis is often hard to get.

An amyloid PET scan provides direct evidence of the amyloid plaques that are hallmarks of Alzheimer's disease, making it potentially a valuable tool in clarifying an uncertain or difficult diagnosis. At this time, brain amyloid PET scans are not reimbursed by Medicare or private insurance, who have expressed uncertainty about their potential benefits.

In 2016, the Alzheimer's Association launched the Imaging Dementia-Evidence for Amyloid Scanning (IDEAS) Study, the largest ongoing study in dementia research, to test the impact of a brain amyloid PET scan on medical management of people where the cause of their dementia or cognitive impairment is challenging to diagnose. Working with the Alzheimer's Association to develop parameters, Medicare agreed to provide coverage for one amyloid PET scan per Medicare recipient enrolled in the study.

We are thrilled to announce the study met its recruitment goal to provide more than 18,000 Medicare participants with amyloid PET scans and has closed enrollment ahead of schedule. Reaching enrollment two months early demonstrates there is a great demand for amyloid PET as a tool to assist with proper diagnosis and improve care for people with Alzheimer's.

Promising preliminary results reported at AAIC 2017 suggested that brain amyloid PET imaging allows for more accurate detection or exclusion of Alzheimer's, leading to better medical management. The interim results analyzed changes in patient management in nearly 4,000 IDEAS Study participants - Medicare beneficiaries age 65+ with mild cognitive impairment (MCI) or atypical dementia.

After receiving the PET scan results, changes in medical management were seen in more than two-thirds (67.8%) of MCI patients, and just about the same percentage (65.9%) of people with dementia. The original hypothesis was that having amyloid PET scan results would change medical management in 30% of cases. The interim results suggest we are well on track to see an effect of at least that magnitude, and perhaps greater, when the final results are available.

The Alzheimer's Association is grateful to CMS for their support of the IDEAS Study, as the results indicate that access to this technology can make a real difference in the care of people with MCI and dementia. We are hopeful that at the end of the IDEAS Study we'll have enough evidence to demonstrate to CMS that it is important to provide coverage for the PET scan when appropriately used in the diagnosis of dementia.The results of all study participants is expected in Fall 2018.

Maria Carrillo, Ph.D., is the Chief Science Officer of the Alzheimer's Association

The IDEAS Study is a led by the Alzheimer's Association and managed by the American College of Radiology.