Will You Get Tested For Alzheimer’s?
10 CommentsBy Ed Silverman // August 11th, 2010 // 7:55 am
Alzheimer’s disease made the news in a big way yesterday, thanks to a study that found a spinal fluid test that is apparently 100 percent accurate in identifying patients who have significant memory loss and are developing the disease. The study in the Archives of Neurology (here’s the abstract) was hailed as a breakthrough, since accurate and predictive biomarkers are so hard to come by.
As we noted, this development should make it easier for clinical research to accelerate. People who have undergone spinal fluid tests can be enrolled in studies that are run to better solicit info about those who are developing symptoms and, later, to track the progress of drugs that are being developed to treat or prevent Alzheimer’s.
The finding comes just one month after new diagnostic guidelines were proposed at the Alzheimer’s Association International Conference to use brain scans to detect the disease before patients have developed any obvious memory problems or other symptoms. But brain scans are not commercially available; spinal fluid tests are. This means one can get diagnosed even though treatment is lacking.
This raises an interesting proposition that, as Mark Senak in Eye On FDA movingly noted, harks back to the early days of the AIDS crisis, when getting a positive test result meant a heartbreaking slide toward death with no hope of treatment in sight. Of course, the pharmaceutical industry eventually responded with myriad development projects and a similar effort is already under way for Alzheimer’s. But what will you do?
Will You Get Tested For Alzheimer's
- No (66%, 87 Votes)
- Yes (34%, 45 Votes)
Total Voters: 132
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Elmore
This is getting really out of hand. The senior director of medical and scientific relations at the Alzheimers Association, Maria Carillo, has noted that the tests might be useful in patients who are already showing signs of AD:
“This just reinforces the recommendation by [Alzheimer's working groups] saying that biomarkers can actually be incorporated today into clinical practice in order to add a certain piece to the diagnosis if patients are already presenting with something that looks like Alzheimer’s.”
This is nothing like the same as using the tests in people who have no signs of the disease. In fact she says they are not to be used for that:
But, Cosentino cautioned, “amyloid beta is not ready to be used as a disease biomarker. Not everyone who has high levels of plasma amyloid beta will demonstrate Alzheimer’s disease or cognitive decline.”
In the Archives of Neurology study, over a third of cognitively normal subjects had biomarkers for AD. Although the investigators “optimistically” suggested that they just might not have symptoms yet, this could also be similar to the nun’s study, where many people who were cognitively normal at death had plaque at autopsy.
pharmavet
Any physician on these boards who has performed a lumbar puncture, or any patient that has undergone such procedure will tell you that it is a rather unpleasant experience, especially in older adults, where the presence of spinal osteophytes makes it tricky to get a spinal needle through the intervertebral space. From the assay precision standpoint, the assay seems to have a high degree of sensitivity (90% true positive rate) but a low degree of specificity (36% false positive rate in normals). Given these numbers, and the technical challenges of an LP in older individuals, I would be hesitant to recommend this test without seeing the results of a much larger study first.
Elmore
Pharmavet–Maybe you can answer this. I understand that sensitivity is really not worth much unless the study population mirrors the general community. In other words, if you use a test for something in a group likely to have it, the sensitivity is likely to be much higher than if you use it in a general population. I didn’t find any information in the abstract that could address this. Any ideas?
Justice in MI
As someone who’s been “punctured,” it would take a lot to get me back there (so to speak) again.
Beyond making a differential dx in the presence of symptoms, it would depend on the sensitivity of the test (especially rate of false positives, as others have suggested) and genuine, serious implications re: treatment decisions and other planning.
JaT
I wouldn’t have this test, but then, I also wouldn’t take advantage of knowing my future up until the date, time, and cause of my death either. Some things are best left alone.
This does make me wonder, however, based on the drugs I take to control my epilepsy - and based on already having some memory issues with no detectable physical signs of atrophy, does this test differentiate between drug induced memory loss and alzheimers? Maybe it could be used as a tool in the neuro drug approval process.
Does no one fear that a possitive test result in any area of system breakdown could result in a lower level of care one day? Like an alcoholic on a liver transplant list.
Off Topic-
When the decision was coming down I explained here why (I believed) the study resulting in the suicidal ideation warning for epilepsy drugs was BS. It burned me to make that pro-pharma argument so soon after Pfizer and FDA messed me up. It burned me more that I had to keep explaining to my loved ones that, as sick and scared as I was, I was not suicidal.
Not being smug (really couldn’t feel less smug) but maybe someone who actually takes these products for epilepsy should be participating in the decisions about them. I’m not applying. Grrr.
http://www.bloomberg.com/news/2010-08-04/epilepsy-drugs-don-t-increase-risk-of-suicide-despite-warning-study-finds.html
Karl in FL
My question is the insurance issue. In having the test, and assuming a positive response, do I become ineligible for insurance at some time in the future? Or, are my rates higher?
snugpharma
worth noting:
Editorial: Biomarkers Aid Diagnosis of Alzheimer’s Disease
“The article by De Meyer et al in this month’s issue of the Archives presents a novel method of analyzing cerebrospinal fluid (CSF) biomarker data and determining how these data map onto the clinical diagnoses of Alzheimer’s disease, mild cognitive impairment and healthy control subjects,” write A. Zara Herskovits, M.D., Ph.D., of Brigham and Women’s Hospital, and John H. Growdon, M.D., of Massachusetts General Hospital, Boston, in an accompanying editorial.
“To date, cerebrospinal fluid analyses have not been a routine component of assessment and care for patients with cognitive impairments and suspected Alzheimer’s disease in the United States. There is now ample evidence that these measurements have value; physicians need to formulate when and how to incorporate cerebrospinal fluid measurements into their practice,” they write.
“Gazing into the future when there are neuroprotective medications for Alzheimer’s disease, we can envision a recommendation that cerebrospinal fluid analyses be implemented as a screening test to identify clinically healthy individuals at risk for mild cognitive impairment and Alzheimer’s disease. The information gained would enable early application of treatments to delay onset of symptoms or slow progression of cognitive impairments.”
Linda
Scans and spinal tap testing are similar to some existing genetic tests for Alzheimer’s disease. The common factor- a lack of accuracy. However, I foresee that these unreliable new tests will be used regardless to the advantage of big Pharma to try out drugs on unsymptomatic people who test positively for the disease. In all the discussions about these tests, the issue of what it would be like to receive a false diagnosis has not been raised. People who receive a diagnosis of Alzheimer’s would, no doubt, worry about every memory lapse and question their every decision. Others (e.g employer, family member, etc.) will treat them as though they have the disease preventing them from living fully or worse. In the end, they may never develop the disease. The ethical implications of a false diagnosis are tremendous.
Justice in MI
Thanks, snug. This seems to me to be the operative phrase: ““Gazing into the future when there are neuroprotective medications for Alzheimer’s disease…”.
Indeed, depending on potential AEs, such meds could be given empirically, and no tap necessary. Certainly concur with Linda about the implications of false diagnosis. The attendant risks, which are considerable, would again have to be outweighed by potential considerable benefit, in a future which (by definition) isn’t yet here.
pharmavet
Elmore, you’re correct on assay precision. You could Google the topic and come up with some good, albeit technical articles.
Re a single assay being the “holy grail” of AZ diagnosis, I was excited when one of my fellow grad school alumni discovered the genetic linkage between apoE4 and Alzheimer’s Disease, but it is also abundantly clear that this is a multifactorial disease, hence my caution on a single biomarker assay.
http://www.fasebj.org/cgi/content/abstract/10/13/1485