Language Processing in Neurodegenerative Diseases Semantic, Phonological, and Grammatical Impairments in Alzheimer’s Disease, Parkinson’s Disease, and Frontotemporal Lobar Degeneration – A Linguistic Overview
Disorders of language and/or communicative abilities in neurodegenerative diseases are a common phenomenon. Over the past few decades, there has been a growing interest in language performance connected to these diseases. To date, studies in the field of language impairments in Alzheimer’s disease (AD), Parkinson’s disease (PD), and frontotemporal lobar degeneration (FTLD) have focused mainly on particular aspects of language processing in the isolated disease or on comparing certain language tasks in two neurodegenerative diseases. To enable a better understanding and comparison of the underlying linguistic deficits in all three disorders, this paper focuses on phonological, semantic, and grammatical processing in each of the disorders. A review of the literature on language processing deficits reveals that phonological, semantic, and grammatical processing is impaired in the early stages of AD, PD, and FTLD, and that the underlying deficits are some- times linguistic in nature. Language disorders, however, may also reflect cognitive deficits, such as short-term verbal memory impairments, attention deficits, and reduced switching capacities, all of which have an impact on language processing.