Gamma tACS in Attention-Deficit/Hyperactivity Disorder

NCT07145593 | Enrolling By Invitation

• 1 other identifier: E-10840098-202.3.02-4603
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

Attention-Deficit/Hyperactivity Disorder (ADHD) is a common neurodevelopmental disorder characterized by symptoms of inattention, impulsivity, and hyperactivity. These symptoms are often associated with impairments in executive functions and working memory, which are essential for goal-directed behavior and cognitive control. Deficits in these domains can significantly hinder individuals' academic, social, and daily functioning. Gamma oscillations (30-80 Hz) play a crucial role in cognitive integration, attention, and memory processes, and are thought to emerge from the balance between excitatory and inhibitory neuronal activity. Transcranial Alternating Current Stimulation (tACS) is a non-invasive brain stimulation technique that modulates neuronal activity through rhythmic electrical currents. Recent studies suggest that gamma-frequency tACS applied to the prefrontal cortex can enhance cognitive performance and attentional processes. In individuals with ADHD, disrupted gamma connectivity and reduced regional gamma power have been associated with attentional deficits. Therefore, gamma tACS may modulate both regional activity and long-range functional connectivity, offering a promising neuromodulation strategy to alleviate ADHD symptoms. In this context, the present study aims to investigate the effects of bilateral gamma-frequency tACS applied to the prefrontal cortex on attention and executive function performance in individuals with ADHD. Changes in gamma oscillatory activity will be measured using EEG to assess the neurophysiological impacts of stimulation. The study seeks to evaluate whether gamma tACS can serve as a targeted, evidence-based intervention to address the neurofunctional deficits observed in ADHD, potentially offering a novel therapeutic approach.

Conditions

Attention Deficit Disorder With Hyperactivity (ADHD)

Keywords

gamma; EEG; tACS

Outcome Measures

Primary Outcomes (4)

• Öktem Verbal Memory Test

  Öktem Verbal Memory Test is a test of verbal memory processes, developed and validated by Öktem in 1992. It is designed to measure various variables related to memory.

  Pre-tACS Baseline (prior to stimulation) / Post-tACS (within 30 minutes after stimulation)

• Forward and Backward Digit Span

  This test, which is a subtest of the Wechsler Memory Scale, was developed to assess overall attention. It consists of two stages. The first stage evaluates the forward digit span, composed of random sequences ranging from 2 to 8 digits. In the second stage, the backward digit span is assessed using random sequences of 2 to 7 digits. In the first stage, numbers are read aloud with one-second intervals, and participants are expected to repeat the sequences exactly as presented. In the second stage, numbers are again read with one-second intervals, but participants are required to repeat the digits in reverse order. The test is terminated if the participant makes consecutive errors. The forward digit span assesses sustained attention, while the backward span also evaluates working memory performance.

  Pre-tACS Baseline (prior to stimulation) / Post-tACS (within 30 minutes after stimulation)

• Verbal fluency tests

  Verbal fluency tests measure the ability to generate words within a specific category over a limited time period. Verbal fluency performance has been associated not only with general language skills and semantic memory functions but also with executive functions such as attention, working memory, and processing speed. In this study, semantic and phonemic fluency tasks will be used.

  Pre-tACS Baseline (prior to stimulation) / Post-tACS (within 30 minutes after stimulation)

• Resting State EEG and TASK EEG

  The EEG recordings of the participants will be conducted using a BrainAmp 64-channel DC system. A 64-channel EasyCap will be used. AFz will serve as the ground electrode, and FCz will be used as the reference electrode. Impedance values will be maintained below 10 kOhm. EEG data will be recorded using the BrainVision Recorder software (Brain Products, Munich, Germany) with a band-pass filter set between 0.01 and 250 Hz.A 4-minute eyes-open and a 4-minute eyes-closed resting-state EEG recording will be conducted. EEG will also be recorded during the 2-back task and the memory task. 2-back Task: A visual n-back task will be administered to assess working memory. The task load will consist of 8-minute sessions. Memory Task: The memory task, which involves both encoding and retrieval of episodic information, will be examined using a visual memory paradigm presented to the participants.

  Pre-tACS Baseline (prior to stimulation) / Post-tACS (within 30 minutes after stimulation)

Other Outcomes (2)

• The Self-Reported Attention Deficit Scale

  Baseline

• Montreal Cognitive Assessment (MoCA)

  Baseline

Study Arms (5)

80 Hz Group

EXPERIMENTAL

Transcranial alternating current stimulation (tACS) at 80 Hz gamma frequency will be applied to the bilateral dorsolateral prefrontal cortex (DLPFC). Each session will last 20 minutes. A total of five sessions will be conducted.

Device: Application tACS- 80 Hz

6-80 Hz Group

EXPERIMENTAL

Transcranial alternating current stimulation (tACS) at 6-80 Hz theta- gamma frequency will be applied to the bilateral dorsolateral prefrontal cortex (DLPFC). Each session will last 20 minutes. A total of five sessions will be conducted.

Device: Application TACS - (6-80 Hz)

Sham Group

SHAM COMPARATOR

Transcranial alternating current stimulation (tACS) sham will be applied to the the bilateral dorsolateral prefrontal cortex (DLPFC). Each session will last 20 minutes. A total of five sessions will be conducted.

Device: Application TACS- Sham

40 Hz Group

EXPERIMENTAL

Transcranial alternating current stimulation (tACS) at 40 Hz gamma frequency will be applied to the bilateral dorsolateral prefrontal cortex (DLPFC). Each session will last 20 minutes. A total of five sessions will be conducted.

Device: Application tACS -40 Hz

Individual Gamma Group

EXPERIMENTAL

Transcranial alternating current stimulation (tACS) at ındividual gamma frequency will be applied to the bilateral dorsolateral prefrontal cortex (DLPFC). Each session will last 20 minutes. A total of five sessions will be conducted.

Device: Application TACS- Individual Gamma Hz

Interventions

Application tACS- 80 Hz DEVICE

In this study, a single 20-minute session of tACS will be administered over the bilateral dorsolateral prefrontal cortex (DLPFC) at various gamma frequencies (80 Hz).The anodal surface electrode will be placed over the left DLPFC (F3 according to the 10-20 system), and the cathodal electrode over the right DLPFC (F4).

80 Hz Group

Application tACS -40 Hz DEVICE

In this study, a single 20-minute session of tACS will be administered over the bilateral dorsolateral prefrontal cortex (DLPFC) at gamma frequencies (40 Hz). The anodal surface electrode will be placed over the left DLPFC (F3 according to the 10-20 system), and the cathodal electrode over the right DLPFC (F4).

40 Hz Group

Application TACS - (6-80 Hz) DEVICE

In this study, a single 20-minute session of tACS will be administered over the bilateral dorsolateral prefrontal cortex (DLPFC) at theta- gamma coupling frequencies ( 6-80 Hz). The anodal surface electrode will be placed over the left DLPFC (F3 according to the 10-20 system), and the cathodal electrode over the right DLPFC (F4).

6-80 Hz Group

Application TACS- Individual Gamma Hz DEVICE

In this study, a single 20-minute session of tACS will be administered over the bilateral dorsolateral prefrontal cortex (DLPFC) at individual gamma frequencies . The anodal surface electrode will be placed over the left DLPFC (F3 according to the 10-20 system), and the cathodal electrode over the right DLPFC (F4).

Individual Gamma Group

Application TACS- Sham DEVICE

In this study, a single 20-min tACS session will be applied over the bilateral dorsolateral prefrontal cortex (DLPFC) in a sham application. The anodal surface electrode will be placed over the left DLPFC (F3 of the 10-20 system) and the cathodal electrode will be placed over the right DLPFC (F4).

Sham Group

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Being between 18 and 40 years of age
• Receiving an ADHD diagnosis
• Scoring above 25 on the Montreal Cognitive Assessment (MoCA)
• Being right-handed

You may not qualify if:

• Use of medications with sedative or stimulant effects
• Presence of metal brain implants or a pacemaker

Sponsors & Collaborators

• Medipol University: lead

Study Sites (1)

Medipol University Istanbul

Istanbul, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Attention Deficit Disorder with Hyperactivity

Condition Hierarchy (Ancestors)

Attention Deficit and Disruptive Behavior Disorders; Neurodevelopmental Disorders; Mental Disorders

Study Officials

• Lütfü Hanoğlu

  Medipol University

  STUDY DIRECTOR

• Suat Yılmaz

  Medipol University

  PRINCIPAL INVESTIGATOR

• Gülsüm Uzer

  Medipol University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: BASIC SCIENCE
• Intervention Model: FACTORIAL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: July 30, 2025
• First Posted: August 28, 2025
• Study Start: October 1, 2025
• Primary Completion: December 30, 2025
• Study Completion (Estimated): December 30, 2027
• Last Updated: August 28, 2025

Record last verified: 2025-08

Locations

TU (1)