### Syntactic Abilities in svPPA II: Clinical Factors and Neuropsychological and Neural Correlates  
Some studies indicate that a syntactic deficit can manifest with progress of the disease. Such evidence comes both from spontaneous speech and constrained tasks. [PERSON] et al. (2014) report a time effect (disease duration) on the decline of speech fluency and grammar in addition to neuropsychological measures for patients with nf/aPPA (to a greater extent) and patients with the semantic variant, the logopenic variant and bvFTD (to a lesser extent). In particular, svPPA patients with 3.4 years of disease duration did not differ from the healthy controls concerning the proportion of grammatically well-formed sentences and the proportion of dependent clauses (as a measurement of syntactic complexity), whereas the difference was significant concerning both measurements for the same patient group tested at a later time (6.3 years of disease duration). [PERSON] et al. (2017) tested two patients in several language tests and found that whereas at the beginning of the disease the two patients manifested only a semantic deficit, further language deficits, including syntax and verb morphology, appeared with the progress of the disease and the atrophy to language areas such as the posterior perisylvian, insular and inferior frontal regions. Similarly, [PERSON] et al. (2018) replicated the existence of a syntactic impairment in svPPA using another elicitation task and targeting other structures. In particular, they found that patients with svPPA who performed a picture description task were significantly worse in the production of passive sentences as well as sentences with two objects than the controls, and they patterned together with the nfPPA patients concerning sentences with two objects. Despite failing to produce the target structure, svPPA patients produced 90% grammatical sentences at the first testing time, which declined slightly after one year and reached a significant difference compared with the controls in the third year. Moreover, the svPPA patients in the study of [PERSON] et al. (2013), who did not differ from the nfPPA in measures of syntactic complexity, were more severely affected than the nfPPA patients as measured by the Dementia Rating Scale. Disease duration is not identical to severity, but these findings indicate that syntactic impairment can manifest in advanced stages of the disease. These findings are in accordance with studies that suggest that patients suffering from different types of PPA tend to manifest indistinct patterns of language performance in neuropsychological tests as the disease progresses ([PERSON] et al., 2017). Some studies failed to show a duration of disease effect. [PERSON] et al. (2018) addressed the issue of decline in language performance in svPPA using an anagram task eliciting the production of active and passive sentences as well as wh-questions (e.g., _Who is the boy pushing?_) in three different time points. Whereas the svPPA patients did not differ from the controls in the production of actives and passives, they showed significantly worse performance in the production of wh-questions in all testing times; i.e., the syntactic deficit was independent of the disease duration. Contrary to the above studies, [PERSON] et al. (2018) have shown that longer disease duration in terms of months between first symptoms and examination was related to higher scores in neuropsychological language tests, such as the Boston Naming Task or the Pyramids and Palm Trees Test. Interestingly, longer disease duration was associated also with slower decline. The authors suggest that this surprising finding is related to the rapidity of progression and the severity of the symptoms. Patients with lower rates of progression and, probably, milder symptoms delay to seek medical care, so the disease duration is longer.