Lexical Access in Women with the FMR1 Premutation
Abstract
Background: Emergent research indicates that women carrying the FMR1 premutation (FXpm) may encounter difficulties in language skills, including increased dysfluencies, a reduction in the quantity and diversity of words produced, and increased word retrieval errors with age (Sterling et al., 2013; Bredin-Oja et al., 2021). Objectives: The present study aims to assess semantic and phonological lexical access skills in FXpm women as well as to examine the impact of cognitive load (time pressure) on lexical access. Methods: Forty-two FXpm women and 25 control women, aged 26-65 years (M=46.22, age-matched: p=.115), participated. The Network Production Task (Oomen & Postma, 2001), featuring visual networks with a target moving through the network at different speeds was employed to elicit language under time pressure conditions. Phonological and semantic naming errors (superordinate/subordinate/coordinate/associative) were coded from transcripts by native raters. Marginal GEE-type logistic models tested the impact of group, condition (fast, slow), and their interaction on the likelihood of lexical errors, controlling for education level and the percent of the network targets completed. Results: Significant group differences were observed in the production of superordinate errors, which reflect target overgeneralization (e.g., “bird” for “flamingo”). FXpm women were 12x more likely to produce superordinate errors compared to controls (p<.001, OR=11.60, 95%CI (3.17, 42.37). No group differences in the production of other lexical error types were observed, and time pressure did not affect the groups differentially. Conclusion: Our study provides initial insight into lexical retrieval difficulties in FXpm women, revealing an increased occurrence of superordinate errors. These types of errors suggest early loss of semantic network information also seen in AD (Marra et al., 2021; Martinez-Nicolas et al., 2019) and other neurodegenerative diseases. The similarity in the pattern of semantic errors in both FXpm and AD emphasizes a possible shared pathogenesis related to β-amyloid production in FXpm and AD. Further investigation of the common factor behind this specific shared semantic degradation is needed.