A methodological critique of the National Institute of Aging and Alzheimer's Association Guidelines for Alzheimer's disease, dementia, and mild cognitive impairments.

In 2011, the U.S. National Institute on Aging published guidelines for clinical diagnostics for Alzheimer's disease dementia. These guidelines define a continuum with three stages-an early, pre-clinical stage with no symptoms, followed by mild cognitive impairment, and a final stage of Alzheimer's disease dementia. This methodological critique examines the validity of this continuum. No studies exist showing the progression of these biomarkers to Alzheimer's disease. There is also a lack of empirical evidence showing how biomarkers determine mild cognitive impairment, which has multiple etiologies. The guidelines fail to explain anomalies where there are biomarkers but no expression of Alzheimer's disease.