[Verbal and gestural communication in interpersonal interaction with Alzheimer's disease patients]

Communication can be defined as a verbal and non verbal exchange of thoughts and emotions. While verbal communication deficit in Alzheimer's disease is well documented, very little is known about gestural communication, especially in interpersonal situations. This study examines the production of gestures and its relations with verbal aspects of communication. Three patients suffering from moderately severe Alzheimer's disease were compared to three healthy adults. Each one were given a series of pictures and asked to explain which one she preferred and why. The interpersonal interaction was video recorded. Analyses concerned verbal production (quantity and quality) and gestures. Gestures were either non representational (i.e., gestures of small amplitude punctuating speech or accentuating some parts of utterance) or representational (i.e., referring to the object of the speech). Representational gestures were coded as iconic (depicting of concrete aspects), metaphoric (depicting of abstract meaning) or deictic (pointing toward an object). In comparison with healthy participants, patients revealed a decrease in quantity and quality of speech. Nevertheless, their production of gestures was always present. This pattern is in line with the conception that gestures and speech depend on different communicational systems and look inconsistent with the assumption of a parallel dissolution of gesture and speech. Moreover, analyzing the articulation between verbal and gestural dimensions suggests that representational gestures may compensate for speech deficits. It underlines the importance for the role of gestures in maintaining interpersonal communication.