We should not distinguish between symptomatic and disease-modifying treatments in Alzheimer's disease drug development

Abstract

The terms symptomatic and disease-modifying have become standard in discussions of Alzheimer's disease therapeutics, yet there is little justification for their use. Currently marketed drugs are presumed to be symptomatic because they lead to some degree of mean improvement over baseline and because of the widespread belief that their mechanisms are limited and their effects are completely reversible. Current trial methodologies cannot distinguish between symptomatic and disease-modifying effects. Furthermore, it is highly likely that many trials will demonstrate a combination of such effects at the level of the trial or at the level of the individual. The forces that drive this distinction are largely social, as opposed to scientific. It would be preferable for drugs to first seek an antidementia claim, preferably on the background of conventional therapies when possible, in trials that are as small and as short in duration as possible. Further refinements would come by demonstration of how substantial and how enduring the antidementia benefits are.