I have written a number of notes about the increasing sophistication of new imaging technologies, particularly PET, in the diagnosis of Alzheimer's disease. A recent article (see: New insight gained into devastating brain ailment) addresses this same topic. Below is an excerpt from it:
A chemical designed by doctors in Los Angeles could give unprecedented insight into the ravages of Alzheimer's disease and provide a new way to test for treatments....Previously the only way to determine if a person suffers from the devastating brain ailment has been to remove some brain tissue or with an autopsy. A new study ...is part of a larger quest to find a better method to diagnose the condition using tracers that can be detected with a positron emission tomography, or PET, scan. The chemical, known as FDDNP, attaches to the abnormal clumps of proteins called amyloid plaques and tau tangles that develop in Alzheimer's sufferers and inhibit messages being processed by the brain. In a[new] study ... [researchers] discovered that the chemical allowed doctors to pick out which of 83 volunteers had Alzheimer's, which had mild memory problems, and which were functioning normally for their age. It was 98 percent accurate in determining the difference between Alzheimer's and mild cognitive impairment. That was far better than the 87 percent success rate for a PET scan test that measured sugar metabolism in the brain, and the 62 percent accuracy rate when doctors used a magnetic resonance imaging scan to gauge brain deterioration.
Although I am generally enthusiastic about the use of biomarker panels for the diagnosis of disease, it does not appear that there has been as much progress recently in the lab diagnosis of dementias as in imaging. A recent on the web comments about this subject thusly:
...specific biomarkers clearly are needed for the differential diagnosis of cognitive impairment in the elderly. What sets age-related disorders like hypertension, hypercholesterolemia and diabetes mellitus apart from Alzheimer's disease is that each has biomarkers that can be followed easily and repeatedly, not simply to diagnose, but also to monitor response and optimize treatment. In contrast, the current role of clinical laboratory evaluation for dementia is exclusionary. The development of such biomarkers is critical to translating efficiently the new therapeutic approaches for AD under development by many research groups into treatments for the millions who suffer from AD.
The good news is that there is a continuing effort in this direction. For example, scientists at Cornell University and the Weill Cornell Medical College have identified 23 cerebrospinal fluid protein biomarkers that may someday be used to identify a person living with Alzheimer's disease. (See: Protein biomarker may predict Alzheimer's). Interested readers about this topic may also want to refer to the following article: Major Biomarker Candidates for Alzheimer's Disease Explored.
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