Overview

This is a single-center, randomized, parallel-group trial evaluating the dose-response relationship of two experimental interventions: manual acupuncture and electroacupuncture for functional constipation.

A total of 72 participants with functional constipation (Rome IV criteria) will be randomly assigned in a 1:1 ratio to either the manual acupuncture group or the electroacupuncture group. Both groups receive acupuncture at bilateral Tianshu (ST25) and Shangjuxu (ST37) points, 30 minutes per session, three times per week for 12 weeks. The electroacupuncture group additionally receives electrical stimulation (continuous wave, 10 Hz, 0.5-4 mA).

The primary outcome is the responder rate at week 12, defined as the percentage of participants with ≥3 complete spontaneous bowel movements (CSBMs) per week. Secondary outcomes include changes in gut microbiota, brain functional connectivity measured by multimodal MRI and fNIRS, and scales.

The study aims to clarify the dose-response characteristics of different acupuncture modalities and their underlying biological mechanisms.

Eligibility

Inclusion Criteria:

• Meet Rome IV diagnostic criteria for functional constipation
• Symptoms present for ≥6 months, meeting diagnostic criteria in the last 3 months
• Mean weekly complete spontaneous bowel movements (CSBMs) ≤2 during 14-day baseline period
• Age 18-75 years
• No use of constipation medications for at least 2 weeks prior to treatment (except rescue medication)
• No acupuncture treatment for constipation in the past 3 months
• Not currently participating in another clinical trial
• Willing and able to provide written informed consent

Exclusion Criteria:

• Constipation secondary to other causes (IBS, organic diseases, medications, endocrine disorders, metabolic disorders, neurological disorders, or gastrointestinal surgery)
• Loose or watery stools (Bristol type 6 or 7) \>1 time during baseline without laxative use
• History of pelvic floor dysfunction
• Use of probiotics, fiber supplements, or laxatives within 2 weeks prior to treatment (2-week washout required)
• Severe hemorrhoids or anal fissures
• Severe or uncontrolled heart, liver, or kidney disease; abdominal aortic aneurysm; hepatosplenomegaly; cognitive impairment; or psychiatric disorders
• Dependence on opioids or anticholinergic drugs
• Red flags: unexplained weight loss \>10% in 3 months, hematochezia or positive fecal occult blood, family history of colon cancer (first-degree relative diagnosed \<50 years), anemia (Hb \<110 g/L), or elevated inflammatory markers
• Contraindications to acupuncture: coagulation disorders or use of anticoagulants
• Pregnancy or breastfeeding
• Unable to comply with follow-up or contraindications to MRI (e.g., cardiac pacemaker, non-titanium aneurysm clips, metallic implants, claustrophobia)