Frontotemporal dementia: a comparative case study of Greek-speaking individuals with the non-fluent and semantic variants of Primary Progressive Aphasia

Abstract

Frontotemporal Dementia (FTD) is an umbrella term that encompasses degenerative disorders of the frontal and anterior temporal lobes that affect behavior and language. FTD overlaps clinically and pathologically with Primary Progressive Aphasia (PPA). PPA is a degenerative syndrome characterized by progressive loss of language function. The consensus criteria for PPA recognize three variants: the non-fluent/agrammatic variant of PPA (nfvPPA), the semantic variant of PPA (svPPA) and the logopenic variant of PPA (lvPPA) (Gorno-Tempini et al., 2011). Each PPA variant has a specific profile of language impairment, different distribution of atrophy on neuroimaging and different likelihood of underlying molecular pathology. Typically, nfvPPA is associated with fronto-insular atrophy, svPPA with atrophy of the anterior and inferior temporal lobe and lvPPA with atrophy of temporo-parietal regions. The most common types of neurodegeneration in PPA are frontotemporal lobar degeneration and Alzheimer’s disease (Spinelli et al., 2017). FTD includes two out of three PPA variants, the nfvPPA and svPPA, as the most typical pathology of these variants is frontotemporal lobar degeneration. PPA is characterized by a more partial and progressive pattern of damage than stroke-induced aphasia and targets areas such as the anterior temporal lobe that are rarely affected by stroke (Mesulam, 2016). Clinical and neuroimaging research on PPA has advanced our understanding of the language network. It has shown, for example, that the left anterior temporal lobe plays a critical role in single word comprehension and object naming and that the traditional ‘Wernicke’s area’ is important for language repetition and sentence comprehension but not single word comprehension (Mesulam et al., 2019). The aim of this study is to compare the clinical presentation of the language variants of FTD, nfvPPA and svPPA, in two Greek-speaking individuals with PPA. Greek is an underrepresented language in the literature on PPA research. It is a highly inflected and stem-based language. To this end, a comprehensive battery of neuropsychological tests and narrative analysis was employed.