Efficacy of acupuncture for patients with Parkinson's disease-related constipation: study protocol for a randomized controlled, double-blind trial.

BACKGROUND

Parkinson's disease (PD)-related constipation represents a prevalent and disabling non-motor symptom that imposes a substantial and growing health and economic burden worldwide. Current management strategies, including dietary modification, probiotics, and pharmacological therapies, often provide limited benefit, with potential adverse effects and minimal improvement in other PD-related symptoms. Acupuncture has emerged as a promising complementary therapeutic approach and has demonstrated preliminary clinical efficacy. However, the underlying biological mechanisms and the potential contribution of placebo responses to therapeutic effects remain insufficiently understood.

METHODS

This randomized controlled clinical trial will enroll 66 patients with PD-related constipation and randomly assign them in a 1:1 ratio to the real acupuncture group or the sham acupuncture group. Participants, acupuncturists, outcome assessors, and statisticians will be blinded to group allocation. The 8-week trial consists of a 4-week treatment period followed by a 4-week follow-up period. The primary outcome is the longitudinal change in the Chronic Constipation Severity Score (CCS) over time. Secondary clinical outcomes include weekly complete spontaneous bowel movements (CSBMs), spontaneous bowel movements (SBMs), Bristol Stool Scale (BSS) scores, and Unified Parkinson's Disease Rating Scale (UPDRS) scores. In addition, exploratory outcomes include levels of short-chain fatty acids (SCFAs), histone deacetylase 1 (HDAC1), and phosphorylated α-synuclein at serine 129 (pS129-α-syn) measured in biofluid samples. Adverse events will be systematically monitored throughout the trial. The study is conducted in accordance with the SPIRIT guidelines.

DISCUSSION: This trial is designed to evaluate the clinical efficacy of acupuncture for PD-related constipation using a rigorously implemented double-blind, sham acupuncture-controlled design. Although the sham acupuncture procedure may itself induce nonspecific physiological and contextual effects, the use of a standardized double-blind control is intended to reduce expectancy-related bias and improve methodological rigor in the assessment of acupuncture-related outcomes. In addition to clinical symptom evaluation, the integration of SCFAs, HDAC1, and pS129-α-syn allows exploratory investigation of potential biological changes associated with treatment. This trial aims to provide multidimensional evidence regarding possible gut-brain axis-related mechanisms involved in acupuncture treatment for PD-related constipation.

TRIAL REGISTRATION: The study protocol was registered with the International Traditional Medicine Clinical Trial Registry (ITMCTR 2026000107) on December 7, 2025. The publicly accessible website is: https://itmctr.ccebtcm.org.cn/mgt/search.