For the first time in 27 years, the Alzheimer’s Association and the National Institute on Aging (NIA) have published new criteria for the diagnosis of Alzheimer’s disease, offering a general framework for early diagnosis but considering existing research unripe for definitive pre-clinical criteria.
The new criteria were drafted by three workgroups associated with the Alzheimer’s Association and the National Institutes of Health (NIH) NIA. The organizations based the criteria on research, presentations and discussions at medical conferences and open comment periods.
Published as a series of articles, the updates redefine the progression of Alzheimer’s as a three-phase process: preclinical Alzheimer’s, mild cognitive impairment (MCI) due to Alzheimer’s and Alzheimer’s-induced dementia.
Although focusing heavily on the flood of preclinical research on the disease, the workgroups only provided a framework intended to assist clinicians in better defining early onset of the disease, eschewing specific preclinical guidelines as important but premature. The preclinical workgroup did propose a research agenda aimed at improving early detection and eventual treatment of Alzheimer’s.
"It is our hope that incorporating scientific knowledge gained and technological advances made over the past quarter century will improve current diagnosis, bring the field closer to earlier detection and treatment and ultimately lead to effective disease-modifying therapies," said William Thies, PhD, chief medical and scientific officer at the Alzheimer's Association. "Development and publication of these articles is a major landmark in the field. That said, publication of these articles is not yet the end of the process of developing new diagnostic criteria for Alzheimer's, but is another major step in the process."
In a 2010 report published by the Alzheimer’s Association, “Changing the Trajectory of Alzheimer’s Disease: A National Imperative,” researchers estimated that an intervention that could postpone the onset of Alzheimer’s by five years would result in a 45 percent reduction in Alzheimer’s cases by 2050, saving Medicare nearly $300 billion.
"If we can definitively determine the risk of developing Alzheimer's dementia in people who have biomarker evidence of brain changes but are not showing outward symptoms, we will open an important window of opportunity to intervene with disease-modifying therapies, once they are developed," Thies argued.
Numerous studies have looked to gain insight into the disease by concentrating on biomarkers, which have thus far provided researchers with critical clues about disease onset, short of precepts for definitive pre-clinical diagnoses.
In a statement released by the Alzheimer’s Association, the organization acknowledged that the principal challenge researchers and clinicians face at present is the establishment of a single, generally accepted formula for pre-symptomatic identification of Alzheimer’s.
"The new guidelines reflect today's understanding of how key changes in the brain lead to Alzheimer's disease pathology and how they relate to the clinical signs of mild cognitive impairment and Alzheimer's disease dementia," concluded Creighton Phelps, PhD, program director of the Alzheimer's disease centers program at NIH. "We are also beginning to be able to detect these changes at a preclinical stage, long before symptoms appear in many people.
“With further research on biomarkers, as set forth in the new guidelines, we may ultimately be able to predict who is at risk for development of mild cognitive impairment and Alzheimer's dementia, and who would benefit most as interventions are developed."