Affiliations: [a] Drug Design & Development Section, Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA | [b] Department of Rehabilitation and Geriatrics, University of Geneva Medical School, Geneva, Switzerland
Correspondence:
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Corresponding author: Robert E. Becker, M.D., C.M., 4 Harbor Ridge Road, P.O. Box 442, South Freeport, ME 04078, USA. Tel.: +1 207 865 4924; E-mail: rebecker2008@comcast.net.
Abstract: Alzheimer's disease (AD) drug developments and clinical trials (CT) remain vulnerable to problems that undermine research validity. Investigations of CT methods reveal how numerous factors decrease active drug-placebo group differences and increase variance, thereby reducing power to reach statistical significance for outcome measure differences in AD CTs. Such factors include, amongst many, inaccuracy, imprecision, bias, failures to follow or lack of operational protocols for applying CT methods, inter-site variance, and lack of homogeneous sampling using disorder criteria. After a review of the literature and survey of a sample of AD and Mild Cognitive Impairment (MCI) CTs, the authors question whether problems of human error preclude AD researchers from continuing their dependence on rated outcome measures for CTs. The authors propose that the realities of AD, especially a probable irreversible progression of neuropathology prior to onset of clinical symptoms or signs capable of differentiating persons at risk for AD from normal aged, require AD investigators and clinicians to privilege biomarkers and encourage their development as surrogate targets for preventive AD treatment developments, testing, and use in clinical practice.
