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Sunday, August 15, 2010

Early Detection of Alzheimer’s Disease? Not Yet, Thanks.

Alzheimer's disease made headlines this week, first with news about a new biomarker test that is able to diagnose the disease with increased accuracy, then with a follow-up story detailing the collaborative model of data-sharing that contributed to the success of recent research.

As I read the news with interest I couldn't help but feel that in our current climate, the manner in which it was reported was somewhat ironic. Just nine months ago experts on the United States Preventive Services Task Force argued that harm, in the form of anxiety related to the detection of breast abnormalities, was too excessive to warrant screening mammograms in forty-year-old women. Just think of the anxiety that will occur if we begin screening asymptomatic adults for Alzheimer's disease.

The unfortunate reality is that despite recent gains in our ability to accurately diagnose Alzheimer's disease, there is still no therapy that has proven effective in preventing its progression. On August 3, 2010 the Annals of Internal Medicine published a summary of this year's National Institute of Health Preventing Alzheimer's Disease and Cognitive Decline Conference.

Alzheimer's disease, the most common form of dementia, is a critical field of study, given the impact that this condition will have on our aging population. At this point the main benefit of earlier and more accurate diagnosis of cognitive impairment and dementia is that it will promote more research on therapeutics on a population level. However, practically thinking, what about the burden that this type of diagnosis could have individuals who go through testing? Is it worthwhile to detect a condition early for which there is currently no definite effective therapy? What would have happened to Ronald Reagan had he had this spinal fluid test when he was sixty years old? Would he have run for president? Would we have elected him? The test may accurately predict Alzheimer's, but does it tell us when? And will happen to health insurance or long-term care insurance coverage for patients after this test is performed?

MRI's are an also an effective means for detecting changes related to Alzheimer's disease, demonstrating amyloid plaque accumulation in patients with Alzheimer's, and distinguishing these patients from those who have other types of dementia, such as vascular dementia, which might be managed differently. However, what about all of our talk of comparative efficacy? Has performing an MRI been shown to alter the outcome of patients with a cognitive impairment or dementia diagnosis? I doubt that it has. I hate to be a cynic, but who will pay for the spinal fluid test, and the MRI, and the neuropsychological testing? And then, the repeat MRIs, and biomarker tests, and neuropsychological tests when the results of the first tests are inconclusive? How frequently will these tests need to be done? These questions are at the heart of the reality that our country faces with respect to the role of medical progress, cost, and health care. But as a physician I advocate mainly for my patient, not for the health care system, so I make these diagnostic decisions collaboratively with my patients, not necessarily with the population level questions in mind.

The Alzheimer's progress is a perfect example of how our country will have to grapple with balancing exciting innovation with the appropriate use of "evidence-based" diagnostics in the coming decade. But how will diagnostics ever become evidence-based if health plans refuse to pay for them? If industry finances expensive clinical trials, should we really be attempting to regulate the cost of their drugs?

In the wonderful book by Audrey Niffenegger, The Time Traveler's Wife, the time traveler witnesses his future death. His fate is unalterable and torments him. Until there is more effective therapy, I, for one, will not be doing the Alzheimer's test. Instead, I will do my best to remain mentally and physically active, control my cardiovascular risk factors, eat my vegetables, consider taking fish oil, take an 81 mg aspirin when I am 65, and wait to see what the next decade of Alzheimer's research will bring in terms of therapeutics. Hopefully innovation will not be stifled by policy change within our country.

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