Apathy and actions- another consideration when theorizing about embodied nature of language in Parkinson's disease

Abstract

Objectives Individuals with Parkinson's disease (PD) have difficulty processing actions or verbs relative to nouns. Verb difficulties are thought to represent the coupling of language and motor networks. However, those with PD also frequently experience apathy. The overlap between apathy and action language difficulties is to date unexplored. Furthermore, whether verb/action fluency difficulty represents verb degradation (semantic/conceptual) or a selective lexical retrieval difficulty has not been determined. Methods In the current study, 20 individuals with PD without dementia completed cued action (verb) and animal (noun) fluency tasks in addition to assessments of apathy, cognition, and motor functioning. Results Individuals who exhibited impairments on action and animal fluency improved around 50% with the provision of cueing. The degree to which action fluency improved with cueing was correlated with behavioral/initiation apathy (r_s=.56) as well as motor dysfunction (r_s=-.57), while no similar relationship was found between those factors and nouns. Conclusions These findings suggest that impaired retrieval of actions and nouns are present in PD, but may have different underlying neuropsychological underpinnings. This provides preliminary support for grounded cognition models, which suggest the brain organizes information around motor, perceptual, and other networks. MESH terms Parkinson Disease, Neurocognitive Disorders, Apathy, Language Disorders, Neuropsychological Tests, Cognition.