Biomarkers to measure treatment effects in Alzheimer's disease: What should we look for?

It is often surprisingly difficult to tell whether a treatment for Alzheimer's disease is effective. Biomarkers might offer the potential of a quantifiable objective measure of treatment effectiveness. This paper suggests several criteria by which biomarkers might be evaluated as outcomes measures. These include biological plausibility, statistical significance, dose dependence, convergence across measures, and replicability. If biomarkers can meet these criteria, then, pending regulatory approval, they may have a role in the evaluation of treatment effectiveness in Alzheimer's disease. If not, their usefulness may be in supplementing, but not supplanting, clinical profiles of treatment effects.