Transcranial Alternating Current Stimulation for Refractory Constipation With Somatic Symptom Disorder (RELIEF-tACS)

January 7, 2026 updated by: Zhifeng Zhao, PhD, Xijing Hospital of Digestive Diseases

A Randomized, Double-Blind, Placebo-Controlled Clinical Trial of Transcranial Alternating Current Stimulation (tACS) for the Treatment of Refractory Constipation Comorbid With Somatic Symptom Disorder

The purpose of this randomized, double-blind, placebo-controlled trial is to evaluate the efficacy and safety of transcranial alternating current stimulation (tACS) in adults with refractory functional constipation comorbid with somatic symptom disorder. This population is characterized by persistent bowel dysfunction despite conventional treatments, frequent reliance on laxatives, and evidence of impaired brain-gut regulation contributing to chronic symptoms.

The study focuses on three primary domains:

Efficacy - Bowel Function:

• Assessment of whether a 4-week course of tACS improves bowel activity, measured by changes in Complete Spontaneous Bowel Movements (CSBM) and overall bowel-movement frequency over the treatment and follow-up period.

Efficacy - Symptom and Quality of Life Burden:

• Evaluation of the effect of tACS on constipation-related severity and patient-reported outcomes, including the Patient Assessment of Constipation-Symptoms (PAC-SYM) and Patient Assessment of Constipation-Quality of Life (PAC-QOL).

Safety and Tolerability:

• Documentation of adverse events associated with tACS, with particular attention to incidence, intensity, and overall patient tolerability compared with sham stimulation.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • China
    • Shaanxi
      • Xi'an, Shaanxi, China, 710032
        • Recruiting
        • Xijing Hospital
        • Contact:
      • Xi'an, Shaanxi, China, 710032

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Diagnosis of Functional Constipation (FC): Subjects must meet the diagnostic criteria for functional constipation as defined by the Rome IV criteria.
  2. Low Frequency of Complete Spontaneous Bowel Movements (CSBM): During the 2-week screening period, subjects must have ≤2 complete spontaneous bowel movements per week.
  3. Poor Response to Previous Treatment: Subjects must have been dissatisfied with prior treatments for functional constipation and have undergone at least 3 months of therapy (including laxatives or other prokinetic agents).

  4. Diagnosis of Somatic Symptom Disorder (SSD): Subjects must meet the DSM-5 diagnostic criteria for somatic symptom disorder (SSD). All subjects will undergo a semi-structured clinical interview based on DSM-5 criteria, conducted by professionals trained in SSD diagnosis.

    • Criterion A: Presence of one or more distressing somatic symptoms that significantly affect daily life.

    • Criterion B: At least one of the following must be met:

      1. Excessive and persistent thoughts about the severity of symptoms;
      2. Persistently high levels of anxiety about health or symptoms;
      3. Excessive time and energy devoted to health concerns or symptoms.
    • Criterion C: Symptoms must persist for at least 6 months.
  5. Age Range: Subjects must be between 18 and 80 years old.
  6. No Concurrent Clinical Trials: Subjects must not participate in any other clinical trials during the study period.
  7. Informed Consent: Subjects must voluntarily agree to participate and sign an informed consent form.

Exclusion Criteria:

  1. Presence of organic diseases (such as tuberculosis, polyps, Crohn's disease, tumors, congenital megacolon, etc.), endocrine disorders (e.g., hypothyroidism), metabolic diseases (diabetes, thyroid dysfunction), or neurological disorders (e.g., Parkinson's disease);
  2. Long-term use of medications that may affect intestinal function or induce constipation, such as Parkinson's drugs (excluding conventional laxatives, antidiarrheals, or intestinal stimulants; during the trial, participants are only allowed to take prescribed emergency medications, with detailed records of usage required);
  3. History of chronic pain or substance abuse, such as opioids;
  4. Diagnosed mental disorders with psychotropic medication use for over 3 months prior to the visit, or history of psychotropic or hormonal medication use for over 3 months;
  5. Individuals at risk of self-harm or suicide, as assessed by a psychiatrist, or those requiring psychosomatic intervention;
  6. History of allergy to psychiatric medications (e.g., fluoxetine), or contraindications to fluoxetine such as liver/kidney impairment or prolonged Q-T interval on ECG;
  7. Pregnant or breastfeeding women;
  8. Patients with benign or malignant tumors or autoimmune diseases;
  9. Chronic conditions requiring long-term medication that may affect quality of life or interfere with examinations/treatment, including cardiovascular diseases, coagulation disorders or regular anticoagulant use (warfarin/heparin), liver/kidney diseases, organ failure, cognitive impairment, aphasia, etc.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: tACS

Electrode placement: Referenced to the forehead (Fpz) and bilateral mastoid regions, covering the prefrontal cortex and related brain-gut axis pathways.

Stimulation parameters: Alternating current, 15 mA intensity, 77.5 Hz frequency.

Dosing schedule: Once daily, 30-40 minutes per session, for 4 consecutive weeks (20 sessions total; Monday-Friday with weekend breaks).
Device: Transcranial Alternating Current Stimulation

Electrode placement: Referenced to the forehead (Fpz) and bilateral mastoid regions, covering the prefrontal cortex and related brain-gut axis pathways.

Stimulation parameters: Alternating current, 15 mA intensity, 77.5 Hz frequency.

Dosing schedule: Once daily, 30-40 minutes per session, for 4 consecutive weeks (20 sessions total; Monday-Friday with weekend breaks).
Placebo Comparator: Placebo

Electrode placement: Same as active-referenced to the forehead (Fpz) and bilateral mastoid regions, to mimic coverage of the prefrontal cortex and related brain-gut axis pathways.

Stimulation parameters: Sham stimulation; the device is programmed to deliver a brief ramp-up and ramp-down at session start (e.g., ≤30 seconds total) to reproduce initial skin sensations, followed by no sustained current (0 mA effective intensity; no therapeutic stimulation).

Dosing schedule: Once daily, 30-40 minutes per session, for 4 consecutive weeks (20 sessions total; Monday-Friday with weekend breaks).

Blinding procedures: Device display, sounds, and electrode preparation identical to the active arm; session duration and operator interactions matched to maintain participant and assessor blinding.
Device: Placebo

Electrode placement: Same as active-referenced to the forehead (Fpz) and bilateral mastoid regions, to mimic coverage of the prefrontal cortex and related brain-gut axis pathways.

Stimulation parameters: Sham stimulation; the device is programmed to deliver a brief ramp-up and ramp-down at session start (e.g., ≤30 seconds total) to reproduce initial skin sensations, followed by no sustained current (0 mA effective intensity; no therapeutic stimulation).

Dosing schedule: Once daily, 30-40 minutes per session, for 4 consecutive weeks (20 sessions total; Monday-Friday with weekend breaks).

Blinding procedures: Device display, sounds, and electrode preparation identical to the active arm; session duration and operator interactions matched to maintain participant and assessor blinding.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
The proportion (%) of patients who achieved an increase of ≥1 CSBM per week compared to baseline for at least 2 out of the 4 treatment weeks.
Time Frame: 1-4 treatment week
1-4 treatment week

Secondary Outcome Measures

Outcome Measure
Time Frame
Proportion of participants achieving an increase of ≥1 CSBM from baseline in at least 2 weeks during follow-up
Time Frame: Weeks 1-4 follow-up; assessed over the 4-week period
Weeks 1-4 follow-up; assessed over the 4-week period
Change from baseline in weekly frequency of spontaneous bowel movements (SBM)
Time Frame: Baseline and each week during Weeks 1-4
Baseline and each week during Weeks 1-4
Change from baseline in weekly frequency of complete spontaneous bowel movements (CSBM)
Time Frame: Baseline and each week during Weeks 1-4
Baseline and each week during Weeks 1-4
Change from baseline in stool consistency (Bristol Stool Form Scale) for weekly SBMs
Time Frame: Baseline and Weeks 3-4
Baseline and Weeks 3-4
Change from baseline in straining score for weekly SBMs (4-point scale: 0=no difficulty, 1=mild, 2=moderate, 3=severe)
Time Frame: Baseline and Weeks 3-4
Baseline and Weeks 3-4
Change from baseline in abdominal bloating severity (5-point scale: 1=none, 2=mild, 3=moderate, 4=severe, 5=very severe)
Time Frame: Baseline and Weeks 3-4
Baseline and Weeks 3-4
Change from baseline in Patient Health Questionnaire-9 (PHQ-9) score
Time Frame: Baseline and Week 4
Baseline and Week 4
Change from baseline in Generalized Anxiety Disorder-7 (GAD-7) score
Time Frame: Baseline and Week 4
Baseline and Week 4
Change from baseline in Patient Health Questionnaire-15 (PHQ-15) somatic symptom score
Time Frame: Baseline and Week 4
Baseline and Week 4
Change from baseline in Patient Assessment of Constipation-Quality of Life (PAC-QOL)
Time Frame: Baseline and Week 4
Baseline and Week 4
Proportion of participants using polyethylene glycol (PEG) as rescue medication
Time Frame: During the 4-week treatment period
During the 4-week treatment period

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Xijing Hospital of Digestive Diseases

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 20, 2025

Primary Completion (Estimated)

July 30, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

December 22, 2025

First Submitted That Met QC Criteria

December 23, 2025

First Posted (Estimated)

January 7, 2026

Study Record Updates

Last Update Posted (Actual)

January 9, 2026

Last Update Submitted That Met QC Criteria

January 7, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • XJLL-KY-20252521

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Access to trial IPD can be requested by qualified researchers engaging in independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a Data Sharing Agreement (DSA). For more information or to submit a request, please contact zhaozhifeng@outlook.com.

IPD Sharing Time Frame

Data requests can be submitted starting 9 months after article publication and the data will be made accessible for up to 24 months. Extensions will be considered on a case-by-case basis.

IPD Sharing Access Criteria

For more information or to submit a request, please contact zhaozhifeng@outlook.com.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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