Masked Faces in Parkinson Disease: Mechanism and Treatment

Facial expressions are complex signals that last only a few minutes and are important for communicating intention, motivation, and emotional states. In humans, a variety of neurological and psychiatric conditions alter the tendency to use facial signals. One of the main symptoms of Parkinson disease (PD) is diminished facial expressivity or "masked facies," which refers to the expressionless appearance of individuals with the disorder. Unfortunately, little progress has been made over the years regarding the basis of "masked faces" or strategies that might improve facial expressivity among individuals with PD. This is unfortunate because the particular symptom can have significant medical and social consequences ranging from misdiagnosis of depression to the misattribution of negative emotional states and motivation by family members and healthcare providers. The goal of this trial is to study the effectiveness of a novel, behavioral treatment approach-high intensity respiratory muscle strength training (MST)-for blunting of facial expressions in people with PD. The MST device, a mouthpiece that the participant uses to inspire against resistance, may improve the strength and mobility of muscles around the mouth that are involved in forming facial expressions. Study participation includes screening, baseline evaluations, 4 weeks of behavioral intervention, immediate post-treatment followup, and a 3-month follow-up. Participants will be randomly assigned to take part in high intensity respiratory MST, or a Sham MST. Participation in the study will last for approximately 5 months.