Archived Issues
2002, Volume 13, Number 1
Alzheimer's Disease Testing
by David M. Keren, M.D.
Alzheimer's Disease is a devastating condition that has been increasingly recognized in the past decade. It is an insidious dementia with a gradual onset that progresses relentlessly. Clinically, it is characterized not only by loss of memory, but also changes in mood and behavior. The differential diagnosis for dementia includes evaluation of vascular disease, endocrine conditions, and medications that an individual is taking. Nonetheless, because Alzheimer's Disease is the most common form of dementia recognized today, it is usually at the top of the list.
The neuropathological studies of brains from victims of Alzheimer's Disease demonstrate an inflammatory process with clusters of inflammatory cells, microglia. In addition, there is local activation of complement and production of cytokine-mediated acute phase reactant proteins.
The diagnosis today is based on the clinical assessment of the dementia. It relies on a careful history and physical examination as well as a neurologic and psychiatric evaluation. Because we currently lack definitive genetic testing, and because of the association within families, various researchers have looked for tests that can be performed on blood, cerebrospinal fluid or urine. So far, there is no test approved by the Food and Drug Administration (FDA) for screening or for the early detection of Alzheimer's Disease.
Yet, there are some tests that companies market to physician's offices. One is a test for Neural Thread Protein (also called AD7C) that is not FDA approved. The most objective information that we found about this test is on the Web Site for the Alzheimer's Association. They note the AD7C test has not been proven to be an accurate exclusion test for Alzheimer's disease. AD7C levels then, do not by themselves rule-in or rule-out the condition. Further, they note that among experts in the diagnosis of Alzheimer's disease, there is no consensus that this test is useful. They recommend that the test remain experimental.
We have received requests for other tests. Occasionally someone asks us about testing for Aluminum. Although aluminum was a consideration in the late 1960's, it is no longer thought to be a factor in Alzheimer's disease. Most recently, genetic studies have shown a relationship between the apolipoprotein E (APOE) gene and Alzheimer's disease. APOE should not be used as a predictive test because the mere presence of APOE-e4 gene, considered a risk factor for Alzheimer's, does not indicate that the individual will develop the disease. Furthermore, individuals who lack APOE-e4 certainly can develop Alzheimer's disease. APOE should not be used as a diagnostic test for similar reasons. However, in patients already diagnosed clinically as having Alzheimer's Disease, APOE genotyping may be useful in predicting the response to certain therapeutic agents.
Lastly, there are some testing products, also not FDA approved, that are sold to be administered at home. Because the clinical evaluation is so intricately a part of the evaluation, the Alzheimer's Association caution that such self-administered screening tools should not be used as a substitute for proper clinical evaluation.
We encourage you to visit the Alzheimer Association's web-site for a firsthand look at this and other information. www.alz.org/media/positions/viewpt.htm