This study evaluates the effects of single-session Transcranial Direct Current Stimulation (tDCS) on fear reversal learning in patients with anxiety disorders. Participants will be randomized into four groups to receive either active stimulation targeting specific brain regions (right DLPFC or vmPFC), an active control stimulation, or sham stimulation. The main goal is to determine if modulating these brain areas can improve the ability to update safety and threat associations.
Anxiety disorders are characterized by deficits in fear regulation and cognitive flexibility, specifically the inability to inhibit fear responses when a threat becomes safe (fear reversal). Neurobiological models suggest this is linked to hyperactivity in the right dorsolateral prefrontal cortex (rDLPFC) and hypoactivity in the ventromedial prefrontal cortex (vmPFC). This randomized, double-blind, sham-controlled study aims to verify if tDCS can improve fear reversal performance. The study involves 140 patients with anxiety disorders assigned to one of four arms: Cathodal tDCS over the right DLPFC (inhibitory); Anodal tDCS over the vmPFC (excitatory); Sham tDCS (placebo); Anodal tDCS over the left DLPFC (active control). During the 25-minute stimulation session, participants will perform a computerized fear reversal task. Physiological data (Skin Conductance Response) and subjective anxiety ratings will be recorded simultaneously to assess the intervention's impact on cognitive and emotional regulation.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
140
Current intensity: 2.0 mA. Duration: 25 minutes. Cathode placed over F4 (10-20 system), Anode over contralateral deltoid.
Current intensity: 2.0 mA. Duration: 25 minutes. Anode placed over Fpz (10-20 system), Cathode over Oz.
Current ramps up for 30 seconds and then fades to zero to mimic skin sensation, with no sustained current for the rest of the 25 minutes.
Shenzhen Kangning Hospital
Guangzhou, Guangdong, China
Mean Accuracy Rate in the Reversal Phase of the Fear Reversal Task
The percentage of correct responses during the reversal phase of the computerized task, where participants must inhibit previous fear associations and learn new safety signals. Higher scores indicate better cognitive flexibility.
Time frame: During the intervention (Day 1, approximately 25 minutes)
Reaction Time in the Reversal Phase
The response time (in milliseconds) to the new CS+ (formerly CS-) and new CS- (formerly CS+) stimuli during the reversal phase.
Time frame: During the intervention (Day 1, approximately 25 minutes)
Skin Conductance Response (SCR) Amplitude
The amplitude of physiological skin conductance responses to Conditioned Stimuli (CS+ and CS-), serving as an objective measure of physiological arousal and fear response.
Time frame: During the intervention (Day 1, approximately 25 minutes)
Subjective Anxiety Score (VAS)
Self-reported anxiety levels measured using a Visual Analog Scale (VAS). Scores range from 0 (no anxiety) to 10 (extreme anxiety).
Time frame: During the intervention (Day 1, assessed intermittently during the 25-minute task)
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Current intensity: 2.0 mA. Duration: 25 minutes. Anode placed over F3 (10-20 system), Cathode over contralateral deltoid.