Comprehensive qualitative characterization of linguistic performance profiles in primary progressive aphasia: a multivariate study with FDG-PET

Primary progressive aphasia (PPA) classification relies on profile characterization of quantitatively im-paired/spared performance in language tasks. In this study, we coextracted 8 qualitative types of errors in 67 PPA patients submitted to a comprehensive language assessment. Canonical correlation analysis was applied to simultaneously correlate qualitative errors and brain metabolism, collected with FDG-PET. Re-sults showed the contribution of semantic, syntactic and working memory errors associated with specific correlates of regional metabolic changes. Reduced metabolism in the left fusiform gyrus, anterior-middle and inferior-temporal gyri and middle-temporal pole correlated with an increase of semantic errors. Hy-pometabolism in the left inferior, middle, and superior frontal gyri, insula and right middle-occipital gyrus was related to syntactic errors. Higher metabolism in the bilateral pallidum, putamen, and left thalamus, as well as hypometabolism in the left angular and supramarginal gyri, inferior-parietal lobule, posterior-middle and inferior-temporal gyri and posterior cingulum predicted the increase of working memory errors. A relevant role of working memory subcomponents was associated with distinct neural systems. Patients' profiles are easily represented in a qualitative multidimensional space, in which mixed PPA overlapped with different phenotypes. (c) 2022 Published by Elsevier Inc.

Automated summary

This study investigates the relationship between qualitative errors in language tasks and brain metabolism in PPA patients. The results show that semantic, syntactic, and working memory errors are associated with specific regional metabolic changes. The findings suggest that different neural systems are involved in different subcomponents of working memory. The study also highlights the overlapping profiles of mixed PPA with different phenotypes in a qualitative multidimensional space.