Tai Chi for improving motor symptoms in Parkinson's disease patients: a systematic review of mechanisms.

Background: In recent years, Tai Chi (TC) training has played an increasingly important role in the management of motor disorders in Parkinson's disease (PD) patients. A thorough understanding of the therapeutic mechanisms of TC is crucial for optimizing its clinical efficacy. The long-term practice of TC has been shown to enhance patients' balance and postural stability, thereby reducing the risk of falls and improving their walking ability. Objectives: This systematic review seeks to elucidate the mechanisms through which TC enhances motor symptoms in individuals diagnosed with PD. It also endeavors to conduct a comprehensive review of existing evidence pertaining to this phenomenon. Methods: This systematic review was conducted following PRISMA 2020 guidelines, structured per PICOS (Population: adults with Parkinson's disease; Intervention: Tai Chi, any style/dosage; Comparator: no intervention, usual care, alternative exercise, or pre-post comparison; Outcomes: biomechanical, molecular/metabolic, or neural-network mechanisms linked to motor symptoms; Design: clinical trials reporting ≥ 1 mechanistic outcome). PubMed, Embase, Cochrane Library, and Web of Science were searched in June 2026, yielding 10 eligible studies (6 RCTs, 4 non-randomized) on TC's effects in Parkinson's disease. Results and conclusion: TC was associated with improvements in postural control, balance, muscle strength, and motor symptoms, alongside reductions in muscle tone and enhancements in quality of life in Parkinson's patients. Most proposed molecular, metabolic, and neural-network mechanisms rely on indirect (peripheral biomarker) or single-study evidence rather than direct central measurements, and remain hypothesis-generating. Candidate mechanisms include increased dopamine-pathway markers, regulated inflammatory responses, and altered neurotransmitter-related metabolism. TC may also affect amino-acid, energy, and neurotransmitter metabolism - including enhanced arginine biosynthesis, tricarboxylic acid cycle activity, and adenosine levels - and upregulate peripheral blood glutathione, an antioxidant marker that may offset oxidative stress relevant to dopaminergic neuron survival, contributing to its therapeutic effects. Molecularly, TC was linked to enhanced ubiquitin-proteasome system activity in a single study, but this finding is derived from peripheral blood and requires confirmation. Biomechanically, it improves center-of-pressure displacement and muscle activity; at the neural-network level, it is linked to improved coordination and activation in motor-related brain areas. However, these mechanistic conclusions are preliminary. Most molecular and metabolic evidence is indirect (peripheral biomarkers) and derived from single studies with small sample sizes, requiring confirmation in larger, centrally-measured trials. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42024486254.