Longitudinal gray matter contraction in three variants of primary progressive aphasia: A tenser-based morphometry study

Abstract

The present study investigated the pattern of longitudinal changes in cognition and anatomy in three variants of primary progressive aphasia (PPA). Eight patients with the non-fluent variant of PPA (nfvPPA), 13 patients with the semantic variant (svPPA), seven patients with the logopenic variant (lvPPA), and 29 age-matched, neurologically healthy controls were included in the study. All participants underwent longitudinal MRI, neuropsychological and language testing at baseline and at a 1-year follow-up. Tenser-based morphometry (TBM) was applied to T1-weighted MRI images in order to map the progression of gray and white matter atrophy over a 1-year period. Results showed that each patient group was characterized by a specific pattern of cognitive and anatomical changes. Specifically, nfvPPA patients showed gray matter atrophy progression in the left frontal and subcortical areas as well as a decline in motor speech and executive functions; svPPA patients presented atrophy progression in the medial and lateral temporal lobe and decline in semantic memory abilities; and lvPPA patients showed atrophy progression in lateral/posterior temporal and medial parietal regions with a decline in memory, sentence repetition and calculations. In addition, in all three variants, the white matter fibers underlying the abovementioned cortical areas underwent significant volume contraction over a 1-year period. Overall, these results indicate that the three PPA variants present distinct patterns of neuroanatomical contraction, which reflect their clinical and cognitive progression.

Fig. 1

Mean scores of four language tests, at baseline (light gray) and at follow-up (dark gray), in each of the three PPA variants.

Fig. 2

Transverse, coronal and sagittal slices of the main peak of gray matter (shown in red) and white matter (shown in yellow) contraction in nfvPPA (first row), svPPA (second row), and lvPPA (third row) versus controls. The results are superimposed on a section of the study-specific template. The x, y, and z values reported in the figure represent the position of slices within the Montreal Neurologic Institute (MNI) stereotaxic space. The threshold is set at p < 0.001 uncorrected for display purpose.