Effects of <i>Chaihu-Shugan-San</i> Adjuvant Therapy on Motor and Non-Motor Symptoms in Parkinson's Disease: A Systematic Review and Meta-Analysis

Objective: To evaluate the efficacy and safety of <i>Chaihu-Shugan-San</i> (CSS) as adjunctive therapy for motor and non-motor symptoms in Parkinson's disease (PD).Methods: Six databases (PubMed, Cochrane Library, CNKI, Wanfang, OASIS, and RISS) were searched for randomized controlled trials (RCTs) published through August 2026. Outcomes included Hamilton Depression Rating Scale (HAMD), Unified Parkinson's Disease Rating Scale (UPDRS), total effective rate (TER), Mini-Mental State Examination (MMSE), and adverse reactions. Meta-analyses were performed using Review Manager.Results: Seven RCTs involving 480 patients were included. Compared with conventional medicine alone, adjunctive CSS was associated with lower HAMD scores (SMD=-1.10, 95% CI: -1.64 to -0.55, p<0.0001), lower UPDRS scores (MD=-8.39, 95% CI: -10.64 to -6.15, p<0.00001), and higher TER (RR=1.27, 95% CI: 1.16 to 1.39, p<0.00001). Reported adverse reaction rates were lower with adjunctive CSS (RR=0.49, 95% CI: 0.31 to 0.78, p=0.003), based on two studies. MMSE scores did not differ significantly (p=0.11).Conclusion: Adjunctive CSS may improve depressive symptoms and offer potential benefits for motor and overall symptoms in PD. However, the small number of studies and heterogeneity limit the certainty of these findings. Safety evidence remains limited and is insufficient to establish a reduction in adverse reactions. Further high-quality RCTs are needed.