Reduction of Bradykinesia of Finger Movements by a Single Session of Action Observation in Parkinson Disease

Background. Action observation influences motor performance in healthy subjects and persons with motor impairments. Objective. To understand the effects of action observation on the spontaneous rate of finger movements in patients with Parkinson disease (PD). Methods. Participants, 20 with PD and 14 healthy controls, were randomly divided into 2 groups. Those in the VIDEO group watched video clips showing repetitive finger movements paced at 3 Hz, whereas those in the ACOUSTIC group listened to an acoustic cue paced at 3 Hz. All participants performed a finger sequence at their spontaneous pace at different intervals (before, at the end of, 45 minutes after, and 2 days after training); 8 participants with PD were recruited for a sham intervention, watching a 6-minute video representing a static hand. Finally, 10 patients participated in the same protocol used for the VIDEO group but were tested in the on and off medication states. Results. Both VIDEO and ACOUSTIC training increased the spontaneous rate in all participants. VIDEO intervention showed a greater effect over time, improving the spontaneous rate and reducing the intertapping interval to a larger extent than ACOUSTIC 45 minutes and 2 days after training. Action observation significantly influenced movement rate in on and off conditions, but 45 minutes after training, the effect was still present only in the on condition. No effect was observed after sham intervention. Conclusions. These findings suggest that the dopaminergic state contributes to the effects of action observation, and this training may be a promising approach in the rehabilitation of bradykinesia in PD.