Effects and Mechanisms of Transcranial Direct Current Stimulation Combined with Dialectical Behavior Therapy Skills Training in Adults with Attention-Deficit/Hyperactivity Disorder Abstract Adult attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that frequently persists into adulthood and is associated with substantial impairments in academic, occupational, and social functioning. Although pharmacological treatment remains the primary intervention, some adults with ADHD show limited response to medication or experience adverse effects, highlighting the need for effective non-pharmacological or combined treatment approaches. Dialectical Behavior Therapy Skills Training (DBT-ST), which emphasizes emotion regulation, impulse control, mindfulness, and behavioral organization, has shown potential in the treatment of adult ADHD. However, its therapeutic efficacy may vary across individuals, and strategies to enhance treatment outcomes still require further investigation. In parallel, transcranial direct current stimulation (tDCS), a safe and non-invasive neuromodulation technique, has attracted increasing attention as an adjunctive intervention in psychiatric disorders. Existing studies suggest that combining tDCS with psychotherapy may optimize treatment effects by modulating neural networks related to cognitive control and emotional regulation. Nevertheless, evidence for such combined interventions in adult ADHD remains limited, particularly with respect to rigorous randomized controlled designs and mechanism-based neuroimaging validation. The present study aims to investigate the efficacy and potential mechanisms of tDCS combined with DBT-ST in adults with ADHD. A randomized, double-blind, sham-controlled design will be adopted. Sixty eligible adult participants with ADHD will be randomly assigned to either an active tDCS group or a sham stimulation group, with both groups receiving weekly DBT-ST for ten consecutive weeks. tDCS will be administered over the bilateral dorsolateral prefrontal cortex (DLPFC) with 2 mA current for 20 minutes, prior to each group therapy session. Clinical symptoms, functional outcomes, and cognitive performance will be assessed at baseline, post-intervention, and one-month follow-up using standardized self-report measures and behavioral tasks. In addition, resting-state functional magnetic resonance imaging (rs-fMRI) will be conducted before and after the intervention to examine changes in functional connectivity within prefrontal regulatory networks. This study is expected to clarify whether tDCS can enhance the therapeutic effects of DBT-ST on core ADHD symptoms and related functional outcomes, and whether such effects are associated with improvements in executive function, emotion regulation, and alterations in DLPFC-related resting-state functional connectivity. By integrating clinical, behavioral, and neuroimaging measures, the study seeks to provide preliminary evidence for a novel non-pharmacological combined intervention for adult ADHD and to further elucidate its underlying neural mechanisms.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
60
Transcranial direct current stimulation (tDCS) is administered over the bilateral dorsolateral prefrontal cortex (DLPFC). In the active condition, a constant current of 2 mA is applied for 20 minutes per session, twice prior to each weekly therapy session, for 10 weeks. The anodal electrode is placed over the left DLPFC (F3) and the cathodal electrode over the right DLPFC (F4). In the sham condition, the current is ramped up and down briefly to mimic the sensation of stimulation without delivering an effective dose.
Nanjing Brain Hospital
Nanjing, Jiangsu, China
RECRUITINGChange in ADHD symptoms as measured by the Adult ADHD Self-Report Scale (ASRS)
ADHD symptom severity will be assessed using the Adult ADHD Self-Report Scale (ASRS). The ASRS is a self-administered questionnaire consisting of 18 items. The total score ranges from 0 to 72, with higher scores indicating more severe ADHD symptoms. The primary outcome is the change in ASRS total score from baseline to post-intervention (10 weeks).
Time frame: Baseline to 10 weeks (post-intervention)
Change in executive function performance as measured by the Stop-Signal Task (SST)
Executive function will be assessed using the Stop-Signal Task (SST). The outcome measure is the stop-signal reaction time (SSRT), reported in milliseconds. The change in SSRT from baseline to post-intervention will be analyzed.
Time frame: Baseline to 10 weeks
Change in emotion regulation ability as measured by the Difficulties in Emotion Regulation Scale (DERS)
Emotion regulation will be assessed using the Difficulties in Emotion Regulation Scale (DERS). The DERS is a 36-item self-report questionnaire. The total score ranges from 36 to 180, with higher scores indicating greater difficulties in emotion regulation. The change in DERS total score from baseline to post-intervention will be evaluated.
Time frame: Baseline to 10 weeks (post-intervention)
Change in anxiety symptoms as measured by the Generalized Anxiety Disorder-7 (GAD-7)
Anxiety symptoms will be assessed using the Generalized Anxiety Disorder-7 (GAD-7) scale. The GAD-7 is a 7-item self-report questionnaire. The total score ranges from 0 to 21, with higher scores indicating more severe anxiety. The change in GAD-7 total score from baseline to post-intervention will be evaluated.
Time frame: Baseline to 10 weeks (post-intervention)
Change in resting-state functional connectivity within prefrontal regulatory networks
Resting-state functional connectivity will be assessed using resting-state functional magnetic resonance imaging (rs-fMRI). The outcome measure is the strength of functional connectivity within prefrontal regulatory networks, focusing on the dorsolateral prefrontal cortex (DLPFC), and is expressed as Fisher's Z-transformed correlation coefficient. The change in connectivity from baseline to post-intervention will be analyzed.
Time frame: Baseline to 10 weeks (post-intervention)
Maintenance of treatment effects at 1-month follow-up
Maintenance of treatment effects will be evaluated by reassessing the following clinical and cognitive outcomes at 1-month follow-up and comparing them with baseline values: ASRS total score (range 0-72, higher = worse), SST stop-signal reaction time (milliseconds), N-back d-prime (unitless), DERS total score (36-180, higher = worse), GAD-7 total score (0-21, higher = worse), PHQ-9 total score (0-27, higher = worse), and rs-fMRI DLPFC functional connectivity (Fisher's Z). Each of these measurements will be analyzed as a separate maintenance endpoint, using the same units of measure as defined in the respective outcomes above.
Time frame: 1-month follow-up
Change in depressive symptoms as measured by the Patient Health Questionnaire-9 (PHQ-9)
Depressive symptoms will be assessed using the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 is a 9-item self-report questionnaire. The total score ranges from 0 to 27, with higher scores indicating more severe depression. The change in PHQ-9 total score from baseline to post-intervention will be evaluated.
Time frame: Baseline to 10 weeks (post-intervention)
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