Effectiveness of TDCS Over Broca's Area in Verb Naming: a Randomized, Double-Blind, Crossover Study

I.R.C.C.S. Fondazione Santa Lucia32 enrolled

Overview

This clinical trial investigated whether transcranial direct current stimulation (tDCS) over Broca's area (F5) could improve verb naming abilities in adults with aphasia. Additionally, the study evaluated the stability of the treatment response to tDCS over time. The main questions this study sought to answer were: * Does tDCS improve verb naming abilities compared to inactive (sham) stimulation? * Are the observed effects stable over time? Participants received 10 daily sessions of tDCS over two consecutive weeks (5 days per week). The study included two treatment conditions, separated by one-month washout period: * Active tDCS: Stimulation over Broca's area at 2 mA; * Sham tDCS: Stimulation mimicking the active condition without delivering electrical current. During the treatment, participants were asked to name aloud videos of actions displayed on a computer screen. One month after each treatment condition, follow-up testing was conducted to evaluate the stability of the treatment response.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Enrollment

Conditions

Aphasia Non Fluent Stroke

Interventions

Active treatmentDEVICE

Participants receive anodic tDCS using a battery-driven Eldith (neuroConn GmbH) Programmable Direct Current Stimulator with surface-soaked sponge electrodes (5×7 cm). A constant current of 2 mA is applied for 20 minutes per session. The stimulation targets the left frontal region (F5 of the extended International 10-20 EEG system), corresponding to Broca's area, while the reference electrode is placed over the contralateral frontopolar cortex. tDCS is performed for 10 daily sessions over two consecutive weeks (5 days per week).

Sham StimulationDEVICE

Participants receive sham tDCS using a battery-driven Eldith (neuroConn GmbH) Programmable Direct Current Stimulator with surface-soaked sponge electrodes (5×7 cm). No therapeutic current is applied during the 20-minute session. The electrode placement mimics the active condition, targeting the left frontal region (F5 of the extended International 10-20 EEG system), corresponding to Broca's area, while the reference electrode is placed over the contralateral frontopolar cortex. Sham tDCS is performed for 10 daily sessions over two consecutive weeks (5 days per week).

Outcomes

Primary Outcomes

Action Naming Task

An action naming task was designed to evaluate verb naming performance. Video clips depicting various actions were presented on a 15-inch computer screen at a viewing distance of 1 meter, each preceded by an 800-millisecond fixation point. Participants were instructed to name the action depicted in each clip within a 15-second response window. The examiner manually recorded correct responses. For incorrect responses or failures to respond within the allotted time, the written name of the action was displayed beneath the video, and participants were required to read the name aloud. The video and the written name remained on the screen until the word was read correctly or 40 seconds had elapsed. The task was conducted during 20-minute tDCS sessions, wherein participants received either active stimulation targeting Broca's area or sham stimulation with identical electrode placement but no active current.

Time frame: Verb naming performance was assessed at baseline (pre-treatment), post-treatment (immediately after the 10-day intervention), and at follow-up (one month after each treatment condition) to evaluate both immediate effects and the stability of responses.