Unraveling the contribution of executive functions to language impairment in ALS

Objectives: This study aims to unravel the association between language deficits and executive functions in non-demented amyotrophic lateral sclerosis (ALS) patients by means of 1) assessing the executive determinants of language impairment (LI) and 2) simultaneously testing the effects of both executive and language performances on phonemic verbal fluency (PVF) deficits. Methods: N = 299 non-demented ALS patients underwent the Edinburgh Cognitive and Behavioral ALS Screen (ECAS), being also assessed for behavioral/psychiatric and motor-functional features. Two sets of logistic models were run: the first, regressing an impaired vs. unimpaired performance on each ECAS-Language (ECAS-L) tasks based on each task of the ECAS-Executive Functioning (ECAS-EF); the second, regressing an impaired vs. unimpaired performance on each ECAS-Fluency tasks based on both ECAS-L and ECAS-EF tasks. Within these models, demographic, motor-functional, and psychiatric/behavioral measures were covaried for. Results: Defective Naming and Comprehension performances were predicted by lower scores on the Sentence Completion task (p ≤ 0.002), whilst defective Spelling performances by lower Alternation scores (p < 0.001). Defective performances on Verbal fluency - S and Verbal fluency - C tasks were predicted by lower Backward Digit Span and Sentence Completion scores, respectively (p ≤ 0.008). Discussion: In ALS patients, inhibitory and set-shifting abilities majorly contribute to LI, whilst PVF deficits are mostly linked to dysexecutive features.