The Impact of Beta-band Transcranial Alternating Current Stimulation (tACS) on Impulse Inhibition in Adolescents With Non-suicidal Self-injury

Condition(s) studied

Investigational drug(s) / intervention(s)

Beta-frequency transcranial alternating current stimulation: Active beta-frequency transcranial alternating current stimulation: 20 Hz tACS delivered through a 4×1-ring high-definition electrode montage centered on left DLPFC (F3), 2 mA peak-to-peak, 100 % intensity, gradually ramped up over 30 s, maintained for 20 min, then ramped down over 30 s; two sessions per day with at least 4 h between sessions, repeated for 7 consecutive days (14 total sessions).

sham beta-frequency transcranial alternating current stimulation: Sham transcranial alternating current stimulation: identical 4×1-ring high-definition electrode montage centered on left DLPFC (F3), 2 mA peak-to-peak current ramped up over 30 s and immediately ramped down to 0 mA, followed by 19.5 min of no stimulation to match the 20-min session duration of active tACS; delivered twice daily (≥4 h apart) for 7 consecutive days (14 total sessions).

Study summary

This clinical trial aims to determine whether beta-band transcranial alternating current stimulation (tACS) can improve impulse inhibition in adolescents with non-suicidal self-injury (NSSI) and to evaluate its safety. The primary questions it seeks to answer are:

* Can beta-band tACS significantly reduce the frequency of self-injury and scores on impulsivity scales in adolescents with NSSI?
* What discomfort or medical issues may participants experience during tACS intervention?

Researchers will compare beta-band tACS with sham stimulation (a procedure that mimics the real stimulation without delivering effective current) to verify its efficacy.

Participants will:

* Receive two sessions of either tACS or sham stimulation daily, spaced 4 hours apart, for 7 consecutive days (14 sessions in total).
* Undergo scale assessments, behavioral tasks, and eye-tracking tests before and after the intervention.
* Record any self-injury episodes and adverse reactions, with continuous monitoring and psychological support provided by a professional team.

Eligibility

Primary outcome measure(s)

• Adolescent Non-suicidal Self-injury Assessment Questionnaire (ANSAQ) reduction in the frequency of self-injury — Once at baseline (pre-treatment) and once at the end of treatment on Day 8.
  The ANSAQ is a brief, self-report tool specifically designed for adolescents aged 12-18 to quantify non-suicidal self-injury (NSSI) over the past year. It is used both to screen for clinically relevant self-harm and to track changes in self-injury frequency after an intervention.
• UPPS-P Impulsive Behavior Scale (UPPS-P) — Once at baseline (pre-treatment) and once at the end of treatment on Day 8.
  The UPPS-P is a 59-item self-report questionnaire that measures five distinct facets of impulsivity: Negative Urgency, (lack of) Premeditation, (lack of) Perseverance, Sensation Seeking, and Positive Urgency. Each item is rated on a 4-point Likert scale from 1 (agree strongly) to 4 (disagree strongly); items are reverse-scored so that higher scores indicate greater impulsivity.
• Brief Barratt Impulsiveness Scale (BBIS) — Once at baseline (pre-treatment) and once at the end of treatment on Day 8.
  The BBIS is an 8-item, self-report subset of the well-known Barratt Impulsiveness Scale. Each item (e.g., "I act on the spur of the moment") is answered on a 4-point scale: 1 = rarely/never, 2 = occasionally, 3 = often, 4 = almost always/always. Total scores range 8-32; higher scores indicate greater impulsivity.
• Eye movement index-fixation time — Once at baseline (pre-treatment) and once at the end of treatment on Day 8.
  Recorded with an SMI-RED eye-tracker while participants freely view 60 pictures in the NSSI-cue reactivity paradigm. Each picture (tool cue, use cue, association cue, or neutral cue) is presented for 4 000 ms. The Region of Interest (ROI) is the entire picture area. "Fixation time" is the total duration (ms) that gaze remains within this ROI during picture presentation. Values are averaged across all cue types (or separately for NSSI-relevant vs. neutral cues) at baseline (Day 0) and post-intervention (Day 8). A ≥ 20 % reduction in total fixation time on NSSI-relevant cues relative to baseline is defined as a clinically relevant improvement in inhibitory control.
• Eye movement index-fixation counts — Once at baseline (pre-treatment) and once at the end of treatment on Day 8.
  During the NSSI cue-reactivity paradigm, an SMI-RED eye-tracker records gaze while 60 pictures (tool, use, association, or neutral cues) are each displayed for 4 000 ms. The entire picture is defined as the Region of Interest (ROI). "Fixation counts" is the total number of discrete fixations that fall within this ROI. The score is averaged across all pictures (or separately for NSSI-relevant vs. neutral cues) at baseline (Day 0) and after the 7-day intervention (Day 8). A ≥ 20 % reduction in fixation counts on NSSI-relevant cues from baseline indicates improved impulse inhibition.
• Balloon Analog Risk Task-Total number of Balloon explosions — Once at baseline (pre-treatment) and once at the end of treatment on Day 8.
  In the computer-based Balloon Analog Risk Task (BART), participants are shown 30 virtual balloons one at a time. They press "F" to inflate (pump) each balloon; every pump increases potential earnings by ¥0.5 but also raises the risk of explosion. Explosion points are random (1-128 pumps, mean 64). Participants can press "J" at any time to stop inflating and bank the current reward. "Total number of balloon explosions" is the count of balloons that burst across all 30 trials. Higher numbers reflect greater risk-taking and poorer impulse control. The score is obtained at baseline (Day 0) and after the 7-day intervention (Day 8); a ≥ 20 % reduction in explosions from baseline is considered a clinically relevant improvement in inhibitory control.

Trial sites (1)

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