The Impact of Anodal tDCS on Verbal and Nonverbal Functional Communication in Subacute Aphasia-An Observational Study.

Background/

Objectives

While a growing number of studies have demonstrated positive effects of adjuvant anodal transcranial direct current stimulation (tDCS) on linguistic performance in aphasia, evidence for corresponding effects on verbal and-in particular-nonverbal functional communication remains absent. This is a critical gap, given that restoring everyday communicative competence is the ultimate goal of speech and language therapy (SLT). In the present observational study, we investigated the add-on effect of anodal tDCS over language-relevant left-hemispheric areas on verbal and nonverbal functional communication in n = 34 individuals with subacute aphasia and examined the relationship between communicative and linguistic change.

Methods

Participants underwent two consecutive two-week therapy phases (P1, P2), each consisting of 10 SLT sessions. Severity-specific linguistic and communicative assessments were administered before, between, and after both phases: the Aachen Aphasia Test (AAT; n = 26) combined with the Amsterdam-Nijmegen Everyday Language Test (ANELT, A-scale), and the Bielefeld Aphasia Screening Rehabilitation (BIAS-R; n = 8) combined with the Scenario Test. During P2, SLT was supplemented by online anodal tDCS.

Results

Overall test performance improved significantly more in tDCS-supported P2 compared to P1 (AAT profile level, p < 0.001; BIAS-R mean percentage value (MPW), p = 0.027; ANELT A-scale raw score Version 1, p = 0.081, and version 2, p = 0.038; and Scenario Test total score, p = 0.003). Significant correlations between AAT profile level and ANELT total scores were found across all time points. Between the MPV and subtests of the BIAS-R and the Scenario total score, there was a tendency toward decreasing correlation levels from T1 to T3.

Conclusions

To our knowledge, this is the first study demonstrating that adjuvant tDCS in subacute aphasia enhances not only linguistic performance but also verbal and nonverbal functional communication beyond SLT alone-assessed with standardized, performance-based, ecologically valid instruments.