### Syntactic Abilities in svPPA II: Clinical Factors and Neuropsychological and Neural Correlates
However, the relation of disease duration with more sensitive and specialized measurements of language abilities, and in particular, syntactic complexity, has not been addressed, to the best of our knowledge. Last but not least, the effect of demographic factors such as age and years of education has scarcely been addressed. Previous findings from longitudinal studies suggest that age and education are not predictors of the decline in neuropsychological language tests such as the Boston Naming Task or the Pyramids and Palm Trees Test [20]. As suggested by the studies above, there is evidence for a syntactic deficit in the language of svPPA patients, which is probably modulated by the duration of the disease and the progress of the atrophy. An unresolved issue is whether general abilities, as measured by neuropsychological instruments, are significantly related to syntactic deficits in svPPA. In particular, it is an open question whether it is a pure syntactic deficit or a result of the semantic deficit. Specifically, it has been suggested that a semantic deficit may lead to reduced syntactic complexity [14]. It is also not clear how the syntactic deficit is related to general language and cognitive abilities, because previous research has yielded contradictory results. [PERSON] et al. [14] did not find a correlation between language decline and decline in the performance in the Mini Mental State Examination in their longitudinal study. [PERSON] et al. [21] found a correlation between two tasks that tapped on syntactic and morphological abilities and general cognitive and language abilities, as measured by the Boston Diagnostic Aphasia Examination (henceforth BDAE, Greek Version [22]) for language abilities and the Addenbrookes Cognitive Examination--Revised (henceforth ACE-R, Greek Version [23]). From a neuroanatomical point of view, it is not excluded that syntactic processing may not always correlate with more general cognitive abilities in svPPA. For instance, [PERSON] et al. [24] found that in svPPA patients, syntax is relatively preserved when the posterior temporal and inferior frontal regions are functionally spared. Concerning neural correlates of svPPA, it has been associated with atrophy in the anterior temporal lobes bilaterally, although damage is larger in the left, manifested as hypoperfusion or hypometabolism on SPECT [1; 2; 6; 25] or lower connectivity [26] in these regions. [PERSON] et al. [27] employed a multimodal imaging approach and explored the integrity of language networks in semantic dementia. Their findings indicate that svPPA was mainly associated with greater damage to the connections that pass through the temporal lobe, while the fronto-parietal connection and the corpus callosum were less involved. Based on this evidence, they suggest that vulnerability of the ventral semantic processing stream of the temporal lobe results in semantic dementia, which is also supported by later studies [28]. On the other hand, a decline in core sentence production has been associated with dysfunction of regions in the frontal lobe, both in stroke aphasia as well as in PPA [29; 30; 31]. Other neuroimaging studies [32] with stroke patients suggest that the left inferior frontal gyrus might not be specialized in sentence processing, but rather, it is a part of the neural network that is responsible for syntactic processing. Although the latter study concerns comprehension and not production, it still remains unclear what is the role of the left inferior frontal gyrus in the processing of sentences, either in production or in comprehension. Therefore, it is unclear which brain region is related to the syntactic impairment in svPPA. In the face of the previous findings, the present study explores the following research questions: (i) whether and to what extent there are syntactic impairments in svPPA and how they are manifested in a language (Greek) with relatively rich morphological paradigms (different noun case endings, verb tense endings, etc.