Body-centred and Object-centred Motor Imagery in Alzheimer's Disease.

OBJECTIVE: Autonomy in patients with Alzheimer's disease (AD) in daily life depends on the preservation of neurocognitive and motor abilities, which decline over time. So far, very few studies have investigated motor representations and their contribution to perception and cognition in AD. METHODS: In the present study, we compared the performance of AD patients to age-matched healthy participants in perceptual and cognitive tasks involving motor imagery. Experiment 1 tested explicit motor and visual imagery through an imagined movement task. Experiment 2 tested body-centred implicit motor imagery through a mental rotation of visual hand task. Finally, Experiment 3 tested object-centred implicit motor imagery through a reachability judgment task. RESULTS: The results showed that, compared to age-matched controls, conscious imagination of a body movement or the movement of a visual stimulus was much longer in AD patients, with no specific difficulty in the motor condition (Experiment 1). Furthermore, response time in AD patients was strongly affected by the angle of rotation of the visual stimuli in the mental rotation of hand task (Experiment 2). Likewise, response time in AD patients increased substantially in the reachability judgment task, but predominantly for stimuli located at the boundary of peripersonal space (Experiment 3). CONCLUSION: As a whole, the data suggested a decline in AD of implicit, but not explicit, motor imagery capacities affecting processing time, but not performance accuracy, in motor-related perceptual and cognitive tasks.

[Verbal and gestural communication in interpersonal interaction with Alzheimer's disease patients]. / Expression verbale et gestualité dans la maladie d'Alzheimer: une étude en situation d'interaction sociale.

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.