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