New guidelines for Alzheimer's diagnosis19th April 2011
Millions more Americans could receive a diagnosis of Alzheimer's disease under newly revised guidelines.
The degenerative brain illness currently affects between 2.4 million and 5.1 million Americans, but the guidelines for diagnosing them may mean many more soon join their ranks.
The guidelines, the first updates for 27 years, were issued by the US National Institute of Ageing and the US' Alzheimer's Association.
They take into account the progression of Alzheimer's as a continuum of stages.
These begin with a "pre-clinical" phase where brain changes may already be occurring, progressing to Mild Cognitive Impairment (MCI), and sometimes to full Alzheimer's.
The stages can be identified through certain biomarkers like the presence of certain proteins in the blood or cerebrospinal fluid.
However, such tests are unlikely to be used in a clinical setting, but only for research purposes.
The guidelines' authors said the updated version was unlikely to affect what happened in a doctor's consulting room with potential Alzheimer's patients.
Author Guy McKhann said they would not change clinical practice. However, MCI will be added as a new diagnosis.
Co-author Marilyn Albert said the addition of MCI as a new diagnosis could mean that the number of patients on the continuum doubled from current numbers.
There are now three clear stages of Alzheimer's, according to the US National Institute on Aging/Alzheimer's Association Diagnostic Guidelines for Alzheimer's Disease.
The first and most severe is Alzheimer's dementia, for which patients must be clearly cognitively and functionally impaired.
Visual, spatial and judgment problems are included in the list of symptoms, along with memory loss.
Johns Hopkins neurology professor McKhann said there were clearer guidelines for a differential diagnosis between Alzheimer's and vascular dementia, which can be caused by stroke.
He said while the diagnosis will still be made by a doctor, with help from someone who knows the patient and perhaps the patient him- or herself, the biomarkers could be used to confirm things.
MCI consists of more modest impairments, mostly in memory, which could increase the risk of Alzheimer's in later years.
Researchers will work towards standardising chemical tests for proteins such as amyloid plaques or nerve damage in the brain.
While not all MCI patients will go on to develop Alzheimer's, Albert said that a very large number did.
The Alzheimer's Association website said progression was not inevitable.
Researchers will make use of the preclinical category to study biomarkers that may be present in the blood or cerebrospinal fluid.
Certain imaging tests that would indicate the build-up of amyloid plaque or damage to nerve cells might also be developed.
Brigham and Women's neurologist Reisa A. Sperling said the guidelines encouraged early detection and early intervention in Alzheimer's cases.
McKhann drew a parallel with the treatment of cancer and diabetes, saying that focusing on those in the later stages of illness was unlikely to be very effective.
Albert said current drugs for Alzheimer's might work much better if given much earlier during the course of the disease.
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Title: New guidelines for Alzheimer's diagnosis
Author: Luisetta Mudie
Article Id: 18279
Date Added: 19th Apr 2011