A Comparison of the Effect of Parkinson's Disease on Verbal and Signed Modalities
Parkinson’s Disease (PD) is the second most common progressive neurodegenerative disorder characterized by deficits in movement. The effects of PD on verbal communicators have long been known, but little is known of its impact on American Sign Language users (ASL). Due to impairments found in the communication of verbal PD communicators, recent studies have investigated impairments found in ASL PD communicators. Studies have shown deficits in prosody, intonation and articulatory approximations created by PD. Possible associations between an ease of articulation and increased difficulties in perception have been theorized. This literature stipulates possible similarities between the effect of PD on verbal and signed modalities. This literature review will analyze the results of previously conducted studies and speculate recommendations for future research.