Historically, Alzheimer’s Dementia (AD) has been defined by visible symptoms, simply because that was all that was available. Around the mid 1990’s, various researchers began pushing for the development of a biologically-based specification of the disease, separate from the manifested symptoms. Among other things, this allows reasoning about the onset of AD before manifestation of symptoms, much like cancer or heart disease. It is believed that the AD process may begin decades before any outward sign of memory loss or other decline.
In 2007, leading AD clinicians formed an international working group (IWG) and proposed using amyloid PET scans, MRI, CSF (cerebrospinal fluid) levels of Aβ and tau, genetic testing, brain structural changes, and subtle cognitive changes to diagnose AD at an earlier stage than before. The NIA/AA (National Institute of Aging, and the Alzheimer’s Association) set up a separate leadership group, and in 2011 it proposed a related set of diagnostic guidelines for AD research that utilized separate criteria for three stages of disease: preclinical AD, mild cognitive impairment, and dementia. The current NIA/AA research framework draws on these two efforts and their personnel.
The workers stress, both in the framework publication and in an associated editorial, that this work is directed at research, and will only slowly begin appearing in the clinical context. But it is expected that the new framework will markedly improve research communication and advances.
Links to media articles on the new framework:
New biological research framework for Alzheimer’s seeks to spur discovery
Alzheimer’s disease redefined: New research framework defines Alzheimer’s by brain changes, not symptoms
New Definition of Alzheimer’s Hinges on Biology, Not Symptoms
Links to two different publications of the framework:
NIA-AA Research Framework: Toward a biological definition of Alzheimer’s disease
NIA-AA Research Framework: Toward a biological definition of Alzheimer’s disease
All the links have been added to Neuro-Psych and to Alzheimers > Neurology & Neuroplasticity
