Brain stimulation (tACS) for adults with stubborn constipation and somatic symptom disorder

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

We will test whether four weeks of gentle brain stimulation (tACS) can improve bowel movements and symptoms in adults with refractory functional constipation and somatic symptom disorder.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 60 (estimated)
• Ages: 18 Years to 80 Years
• Sex: All
• Sponsor: Xijing Hospital of Digestive Diseases (Academic / other)
• Locations: 2 sites (Xi'an, Shaanxi and 1 other locations)
• Trial ID: NCT07323407 on ClinicalTrials.gov

What this trial studies

This randomized, double-blind, placebo-controlled trial enrolls adults with refractory functional constipation and comorbid somatic symptom disorder and randomizes them to 4 weeks of active transcranial alternating current stimulation (tACS) or sham stimulation. Treatment effects will be measured during the treatment period and follow-up, focusing on bowel activity and patient-reported symptom burden. Primary outcomes include changes in complete spontaneous bowel movements (CSBM) and overall bowel-movement frequency, with secondary outcomes capturing constipation severity and quality of life (for example, PAC-SYM). Safety and tolerability will be monitored throughout, and all participants must meet Rome IV criteria for functional constipation and DSM-5 criteria for somatic symptom disorder.

Who should consider this trial

Good fit: Adults who meet Rome IV criteria for functional constipation, have ≤2 complete spontaneous bowel movements per week during screening, have been dissatisfied after at least 3 months of prior therapy, and meet DSM-5 criteria for somatic symptom disorder are ideal candidates.

Not a fit: Patients whose constipation is due to structural, metabolic, or medication-related causes, or who do not meet the Rome IV or DSM-5 SSD criteria, are unlikely to benefit from this intervention.

Why it matters

Potential benefit: If successful, tACS could offer a non-drug option that improves bowel frequency and reduces symptom burden for patients whose constipation persists despite standard treatments.

How similar studies have performed: Related noninvasive brain-stimulation approaches (such as tDCS) have shown mixed early promise for gut–brain disorders, but using tACS specifically for refractory constipation with SSD is largely novel and unproven.

Eligibility criteria

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.

Where this trial is running

Xi'an, Shaanxi and 1 other locations

• Xi'an International Medical Center Hospital — Xi'an, Shaanxi, China (Recruiting)
• Xijing Hospital — Xi'an, Shaanxi, China (Recruiting)

Study contacts

• Study coordinator: Zhifeng Zhao, Dr.

Conditions Functional Constipation; Somatic Symptom Disorder; Refractory Constipation; refractory constipation; transcranial alternating current stimulation