This proposed decision by CMS is jarringly at odds with the bold and aggressive efforts being waged by the NIH, FDA and other agencies in the Obama administration to implement the National Plan to Address Alzheimer's Disease’s goal of preventing Alzheimer's and other dementias by 2025.

Today, it is estimated that one in three seniors dies with some form of dementia. While an estimated 70 percent of dementias are caused by Alzheimer's, 30 percent are caused by another type of dementia. The potential courses of treatment differ for dementias caused by Alzheimer's and those not caused by Alzheimer's. Absent diagnostic tools to distinguish among the causes of dementia, doctors are shooting in the dark in recommending courses of treatment.

The diagnostic tool that can make that differential diagnosis is called an Amyloid PET scan. This scan permits doctors to determine whether a patient with mild cognitive impairment (MCI) or an otherwise hard-to-diagnose form of dementia has a buildup of amyloid in their brains. If present, the patient is more likely to develop Alzheimer’s down the road; if not, the patient is not likely to have Alzheimer’s but some other form of dementia, such as vascular or frontal temporal lobe dementia. By making that specific diagnosis, doctors can recommend a course of treatment appropriate to the patient. This is also significant because about half of people with MCI do not have Alzheimer’s disease and will not progress into dementia.

CMS came to the tentative view that there was not sufficient evidence that use of this diagnostic tool actually improved the health outcomes of patients. We disagree. An accurate diagnosis and appropriately tailored course of treatment of the specific cause of a person's dementia avoids an inappropriate – and often costly – course of treatment. That can only be good for patients. In addition, the proposed standard for reimbursement is higher than has been applied in the past and goes against common sense.

CMS proposes yet further studies of how this product will be used by doctors, and then of how patients appropriately diagnosed (or not) actually do. But the FDA has already found the Amyloid PET scan in question to be safe and effective. Further lengthy and expensive studies will keep this product away from patients and their doctors for years. The manufacturer of the product, Eli Lilly, as well as the Society of Nuclear Medicine and Molecular Imaging and the Amyloid Imaging Task Force has agreed that the product should only be reimbursed in the hard-to-diagnose cases when a patient shows signs of dementia and where clinicians conclude that they need this tool to make an appropriate diagnosis.

If CMS is concerned about the costs of reimbursing for the use of this scan (although it is not authorized to take cost into account), it should simply assure that the use of the product is limited to those small but important hard-to-diagnose cases as defined by independent industry experts in comments to CMS.

Alzheimer's presents a grave and growing threat to millions and millions of Americans and to the solvency of Medicare itself. We need to make sure patients and their doctors have all the safe and effective tools we can to fight against this threat.

A lean forward approach will align CMS with our national commitment to prevent this disease by 2025. A lean backward approach is contrary to the interests of patients. And the use of ever-higher barriers to getting innovative products to market will chill the incentives to industry investment in Alzheimer's.

CMS must move forward, not back, and provide reimbursement for the appropriate use of the test as recommended by experts in the field.

Vradenburg is chairman and co-founder of USAgainstAlzheimer’s, and a member of the Advisory Council on Alzheimer’s Research, Care, and Services; Fillit is the founding executive director and Chief Science Officer of the Alzheimer’s Drug Discovery Foundation; and Weiner is professor of Radiology and Biomedical Imaging at the University of California, San Francisco, and Principle Investigator of the Alzheimer's Disease Neuroimaging Initiative (ADNI).