For the first time in nearly three decades, the criteria used to diagnose Alzheimer's disease have been updated, researchers announced today. The revisions also include guidelines to aid researchers as they investigate the earliest stages of the disease.
When the criteria were first established in 1984, they described only the later stages of Alzheimer's in which patients already show symptoms of dementia, most notably memory loss. The new guidelines view the disease along a continuum: From the early brain changes in which there are no symptoms, to mild cognitive impairment in which patients have memory problems , but are still capable of performing everyday activities, to full-blown dementia.
Development of the new guidelines was led by the National Institutes of Health and the Alzheimer's Association.
They mark the first time the earlier stages of the disease have been formally included in the description of Alzheimer's, the researchers say.
"We've expanded the range of the guidelines to include the very earliest forms of Alzheimer's pathology and symptoms that are clearly not dementia," said William Thies, chief medical and scientific officer at the Alzheimer's Association. "That will allow us to look for ways to identify these earlier stages and treat these earlier stages."
However, very little will change right now in terms of how patients interact with their doctors to be diagnosed with Alzheimer's disease, the researchers say. Much of the new criteria, such as the use of biomarkers to diagnose the disease, are to be employed in research settings only. But the ultimate goal is to drive research to the point where Alzheimer's can be diagnosed years before symptoms show up.
"We wanted to enable the field to move forward by trying to outline how biomarkers can be used in research to move the field faster, because we're all very unsatisfied with the absence of effective drugs right now," Marilyn Albert, of the Johns Hopkins University School of Medicine, who headed the panel to refine the mild cognitive impairment criteria, said in a press briefing about the guidelines. "Part of what we were hoping to do was to stimulate further research and provide a framework for that."
The guidelines break the disease up into three stages:
Preclinical: There is evidence signs of Alzheimer's disease may appear 10 years before the disease is diagnosed . These include brain changes, such as the buildup of the protein amyloid-beta, nerve cell damage and brain shrinkage. Some of these biomarkers might be detected in brain scans and proteins in spinal fluid. But use of biomarkers should remain confined to the realm of research for the time being, the guidelines say. Researchers need a better understanding of how these biomarkers relate to the progress of the disease and how to measure them before they can be used by physicians to assess patients, the drafting scientists note.
Mild cognitive impairment: A portion of those diagnosed with mild cognitive impairment will go on to develop Alzheimer's disease , but researchers can't say who will. Biomarkers such as the use of MRI to detect brain shrinkage might be able to distinguish those who develop the disease from those who don't. In addition, once researchers have ruled out other cases of cognitive impairment, such as a stroke or a tumor, biomarkers could be used to confirm the diagnosis of Alzheimer's disease. However, again, researchers say that these guidelines apply just to research settings.
Alzheimer's dementia: These criteria expand the concept of Alzheimer's dementia beyond just memory loss to include declines in other areas, such as vision/spatial problems, and impaired reasoning or judgment.
If researchers are able to identify Alzheimer's disease early, treatments may work better, scientists who study the disease say.
"We believe that it's critically important when we have more effective drugs to intervene as early as possible," Albert said. "We're quite worried that in fact there might be drugs around now that could be beneficial in the treatment of Alzheimer's disease, but we're using them too late in the disease course. The whole goal of the field is to begin to find ways of identifying people earlier so that when new treatment are developed, we can use them."
The new guidelines were published today (April 19) in Alzheimer's & Dementia: The Journal of the Alzheimer's Association. They were developed by expert panels convened last year by the National Institute on Aging (NIA), part of the NIH, and the Alzheimer's Association. Preliminary recommendations were announced at the Association's International Conference on Alzheimer's Disease in July 2010, followed by a comment period.
Pass it on: Researchers announced new guidelines for the diagnosis of Alzheimer's. Some, such as the use of biomarkers for the disease, apply to research settings only.
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