Disorders of Language Functions and Other Cognitive Functions in Semantic Dementia

The aim of this article is to describe the singularities of linguistic and cognitive disorders as well as changes in behaviour and personality in semantic dementia (SD). SD, also known as the semantic variant of Primary Progressive Aphasia (svPPA), is a progressive neurodegenerative disorder characterised by loss of semantic memory. SD patients usually have difficulty updating previously known words and recognising familiar objects and faces. Clinical symptoms include anomia, multimodal misunderstanding of word meanings, aphasia with preserved speech fluency and associative visual agnosia. The speech of SD patients is characterised by pauses needed to find the missing words, reduced frequency of occurrence of autosemantic words, the presence of semantic paraphasia, increased verb-to-noun ratio and multiple repetitions. As the disease progresses, changes in behaviour and personality are often seen as similar to those observed in frontotemporal dementia.