Need for and challenges facing functional communication as outcome parameter in AD clinical trials.

This paper (1) highlights the relevance of functional communication as an outcome parameter in Alzheimer disease (AD) clinical trials; (2) identifies studies that have reported functional communication outcome measures in AD clinical trials; (3) critically reviews the scales of functional communication used in recent AD clinical trials by summarizing the sources of information, characteristics, and available psychometric data for these scales; and (4) evaluates whether these measures actually or partially assess functional communication. To provide direction for future research and generate suggestions to assist in the development of a valid and reliable functional communication scale for the needs of AD clinical trials, we have included not only functional communication scales, but also related concepts that give thought-provoking impulses for the development of a functional communication scale. As outcome measures for AD clinical trials, the 6 identified papers use 6 different scales, for functional communication and for related concepts. All of the scales appear to have questionable psychometric properties, but still provide a promising basis for the creation of a functional communication scale. We conclude with concrete suggestions on how to combine the advantages of the existing scales for future research aimed at developing a valid and reliable functional communication scale for the needs of AD clinical trials.