How Parkinson's Disease Affects Non-verbal Communication and Language Processing

In addition to difficulties that affect movement, many adults with Parkinson’s disease (PD) experience changes that negatively impact on receptive aspects of their communication. For example, some PD patients have difficulties processing non-verbal expressions (facial expressions, voice tone) and many are less sensitive to ‘non-literal’ or pragmatic meanings of language, at least under certain conditions. This chapter outlines how PD can affect the comprehension of language and non-verbal expressions and considers how these changes are related to concurrent alterations in cognition (e.g., executive functions, working memory) and motor signs associated with the disease. Our summary underscores that the progressive course of PD can interrupt a number of functional systems that support cognition and receptive language, and in different ways, leading to both primary and secondary impairments of the systems that support linguistic and non-verbal communication.