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Brain Imaging, Biomarker Studies Reflected in New Diagnostic Guidelines for Alzheimer’s Disease

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Last week, new criteria and guidelines for diagnosing Alzheimer’s disease was released by the Alzheimer’s Association and the National Institute on Aging (NIA), and published online in the journal Alzheimer’s & Dementia. Long-term studies using brain imaging and biomarker analysis have demonstrated that physiological signs of Alzheimer’s disease begin long before the symptoms of dementia. The new guidelines reflect this growing pool of evidence, although they will have little immediate impact on patients as the tests used to identify Alzheimer’s at the earliest stages of disease aren’t ready for clinical use. Nevertheless, they should provide a framework for researchers and prepare clinicians for the day when more effective treatments become available.

The new guidelines update, refine and broaden widely used guidelines published in 1984 by the Alzheimer’s Association (then known as the Alzheimer’s Disease and Related Disorders Association) and the National Institute of Neurological and Communicative Disorders and Stroke (now known as the National Institute of Neurological Disorders and Stroke). The new guidelines were published in four articles by three expert international workgroups, including ready-to-use clinical diagnostic criteria for Alzheimer’s disease dementia and mild cognitive impairment (MCI) due to Alzheimer’s.

According to Creighton Phelps, Ph.D., Program Director of the Alzheimer’s Disease Centers Program at the National Institutes of Health:

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. 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.

The guidelines divide Alzheimer’s disease progression into three stages: a presymptomatic “preclinical” stage characterized by signature biomarkers that occur years before any disruptions in memory, thinking or behavior can be detected; a mildly symptomatic but pre-dementia stage (mild problems emerge but daily functions can still be performed); and dementia caused by Alzheimer’s.

Currently, there are no clinical diagnostic criteria for the presymptomatic preclinical stage. Additionally, the new criteria doesn’t specify which biomarkers should be considered signatures of preclinical Alzheimer’s disease. Instead, the workgroups propose a research agenda that builds on preliminary data emerging from recent studies, including brain imaging strategies and certain proteins in cerebral spinal fluid.

William Thies, Ph.D., Chief Medical and Scientific Officer at the Alzheimer’s Association, said:

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. 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.

Study: Introduction to the Recommendations from the National Institute on Aging and the Alzheimer’s Association Workgroups on Diagnostic Guidelines for Alzheimer’s Disease.

Study: The Diagnosis of Dementia Due to Alzheimer’s Disease: Recommendations from the National Institute on Aging and the Alzheimer’s Association Workgroup.

Source: Alzheimer’s Association