Predicting Confrontation Naming in the Logopenic Variant of Primary Progressive Aphasia

Background: Naming difficulties are prominent and pervasive in the logopenic variant of primary progressive aphasia (lvPPA) and may reflect its underlying deficits in phonological processing. Importantly, some words appear to be more vulnerable to deterioration than others. We hypothesize that these differences can be explained, in part, by the unique psycholinguistic properties of words. Aims: Our study investigated the role of psycholinguistic properties of words, along with their underlying psycholinguistic factors, in predicting confrontation naming performance in individuals with lvPPA. Methods & Procedures: Naming accuracy data were collected from 14 individuals with lvPPA using the Boston Naming Test (BNT). For each test item, values were extracted for frequency, age of acquisition (AoA), familiarity, word length, phonological neighborhood density (PND), semantic neighborhood density (SND), arousal, and valence. We examined the effects of these psycholinguistic properties on naming accuracy using logistic regression analyses at the individual level and multiple linear regression analysis at the group level. Further, we performed mediation analyses to examine the mediating contributions of related psycholinguistic properties on naming accuracy. Finally, principal component analysis (PCA) was performed to extract fundamental factors of the psycholinguistic properties. These factor scores were entered into regression analyses to investigate their relative contribution to naming accuracy in lvPPA. Outcomes & Results: Age of acquisition emerged as the strongest psycholinguistic predictor of naming accuracy in lvPPA at both the individual and group levels. The influence of AoA on naming accuracy was only partially mediated by frequency. Three principal psycholinguistic factors were extracted from the PCA. These were interpreted as “lexical-semantic usage”, “phonological complexity”, and “emotional intensity”. Results indicated that “lexical-semantic usage” and “emotional intensity” predicted naming performance at both the individual and group levels. Conclusions: Age of acquisition has been associated with the phonological level in models of word naming. The observed psycholinguistic effects on naming accuracy are discussed in the context of phonological deficits in lvPPA and models of word naming.