The Relationship Between Baseline Volume in Temporal Areas and Post-Treatment Naming Accuracy in Primary Progressive Aphasia

Background: Structural imaging has not been used previously to predict the effect of treatment in primary progressive aphasia (PPA).

Aims: This study examined relationships between baseline brain volume and the effects of phonological and orthographic treatments for anomia in PPA. It was predicted that lower baseline volume would be associated with lower post-treatment naming accuracy for treated items and smaller generalization effects.

Methods & Procedures: Twenty-one individuals with PPA participated. The treatment stimuli consisted of nouns that were consistently named correctly at baseline (Prophylaxis items) and/or nouns that were consistently named incorrectly at baseline (Remediation items). All 21 participants had Prophylaxis items, while 10 participants had Remediation items. Naming accuracy for untrained and trained items (Exemplar set 1) was measured. In addition, stimulus generalization was examined by having participants name an alternative exemplar of each untrained and trained item (Exemplar set 2). Correlational analyses focused on the relationships between naming accuracy and volume of regions previously identified as having a role in naming and semantic processing.

Outcomes & Results: Unexpectedly, there were no significant correlations between baseline volume and post-treatment accuracy for treated items. However, baseline volume within the left temporal pole was positively correlated with post-treatment accuracy for Untrained Exemplar set 2 Prophylaxis items, while baseline volume in the left inferior temporal gyrus was positively correlated with post-treatment accuracy for Untrained Exemplar set 1 Remediation items.

Conclusions: These findings suggest that lower volume in the left temporal pole is associated with decline for Untrained items, while lower volume in the left inferior temporal gyrus is associated with a lack of improvement for Untrained items. Possible explanations for the different patterns observed across Exemplar sets are discussed.