The United States announced that guidelines for diagnosing Alzheimer's disease, the most common form of dementia, have been updated for the first time in almost three decades.
The new guidelines acknowledge that memory loss may not be the primary clue in the early stages of the disease, and include three phases for diagnosing the disease instead of one.
The changes reflect a growing body of knowledge about early changes in the brain that may indicate the gradual onset of Alzheimer's, which affects about 37 million people worldwide and has no cure.
Recent advances show changes in the brain as early as 10 years ahead of what has traditionally been the diagnosis of the disease, and the discovery of biomarkers in blood and spinal fluid that may help researchers identify it in advance.
"Alzheimer's research has greatly evolved over the past quarter of a century," National Institute on Aging (NIA) director Richard Hodes said. "Bringing the diagnostic guidelines up to speed with those advances is both a necessary and rewarding effort that will benefit patients and accelerate the pace of research."
The new guidelines are published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association, and were developed by experts at the National Institutes of Health, the NIA and the Alzheimer's Association.
The first preclinical phase applies only in a research setting and outlines brain changes such as amyloid plaque build-up and nerve cell changes that may be present without significant symptoms in the patient.
The second stage outlines mild cognitive impairment symptoms and describes how researchers can check for certain biomarkers in cerebrospinal fluid or use magnetic resonance imaging (MRI) or positron emission tomography (PET) to scan for clues. This stage, too, is mainly for researchers.
The third and final stage is "most relevant for doctors and patients," and outlines how doctors should evaluate the causes and progression of a patient's mental decline.
"The guidelines also expand the concept of Alzheimer's dementia beyond memory loss as its most central characteristic," said a statement released by the Alzheimer's Association ahead of the guidelines' publication.
"A decline in other aspects of cognition, such as word-finding, vision/spatial issues, and impaired reasoning or judgement may be the first symptom to be noticed.
First set of guidelines
The guidelines were first established in 1984, and "defined Alzheimer's as having a single stage, dementia, and based diagnosis solely on clinical symptoms," the association said. "It assumed that people free of dementia symptoms were disease-free."
A report by Alzheimer's disease International issued last year estimated the global economic costs of dementia at 604 billion dollars annually.
Alzheimer's disease usually affects people over age 65.
William Thies, chief medical and scientific officer at the Alzheimer's Association, described the new guidelines as a "major milestone".
"Our vision is that this process will result in improved diagnosis and treatment of Alzheimer's, and will drive research that ultimately will enable us to detect and treat the disease earlier and more effectively," he said.
(Sapa, April 2011)