Below is a comment written by Dr. Norins on ALZForum and in response to a recently published paper titled “Questions concerning the role of amyloid-β in the definition, aetiology and diagnosis of Alzheimer’s disease,” by Morris GP, Clark IA, Vissel B. (Acta Neuropathol. 2018 Nov;136(5):663-689. Epub 2018 Oct 22 PubMed.)
The debate over the criteria for “Alzheimer’s disease” recalls the evolution of those for two other ailments, “pneumonia” and “diarrhea.” At first each was defined mainly by its clinically notable signs and symptoms. Hence each broad term provided interim satisfaction to clinicians and families, but postponed identifying the several agents and mechanisms which could produce similar effects in the lung or intestine.
When laboratory tests became available, additional criteria were added to increase specificity. Stool and sputum samples are cultured to ascertain the particular pathogen, or the absence of any. Thus, we now distinguish diarrhea of salmonella from that of shigella and cholera, and the pneumonia of influenza from that of the pneumococcus and tuberculosis.
It seems that affixing precise criteria and boundaries to the definition of Alzheimer’s and its stages will await the development of generally accepted laboratory tests which reflect initial and progressive brain damage. Meanwhile, why not agree on rough-hewn interim criteria, while recognizing their limitations? – Dr. Leslie Norins
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