BEYOND MOTOR SYMPTOMS: A SYSTEMATIC REVIEW OF THE EFFICACY OF COENZYME Q10 AND VITAMIN SUPPLEMENTATION ON FATIGUE, DEPRESSION, AND COGNITION IN PARKINSON’S DISEASE: A SYSTEMATIC REVIEW

Abstract

Background: Parkinson disease (PD) is a progressive neurodegenerative disorder characterized not only by motor impairment but also by burdensome non-motor symptoms, including fatigue, depression, and cognitive decline. These manifestations substantially reduce quality of life and are often insufficiently managed with dopaminergic therapy. Mitochondrial dysfunction, oxidative stress, and micronutrient deficiencies have been implicated in PD pathophysiology, prompting interest in Coenzyme Q10 and vitamin supplementation as adjunctive strategies for non-motor symptom control.

Objective: To systematically evaluate the effectiveness of Coenzyme Q10 and vitamin supplementation on fatigue, depressive symptoms, and cognitive function in adults with Parkinson disease.

Methods: A systematic review was conducted in accordance with PRISMA 2020 guidelines. Electronic databases including PubMed/MEDLINE, Embase, Scopus, and the Cochrane Library were searched for studies published between 2005 and 2024. Eligible studies included randomized controlled trials, non-randomized clinical trials, and observational studies evaluating Coenzyme Q10 and/or vitamin supplementation in adults with PD. Outcomes of interest were fatigue, depression, and cognition assessed using validated scales. Two independent reviewers performed study selection, data extraction, and risk-of-bias assessment. Due to heterogeneity in interventions and outcome measures, a narrative synthesis was undertaken.

Results: A total of 3,146 records were identified, and 24 studies met inclusion criteria. Sample sizes ranged from 28 to 1,200 participants, with intervention durations between 8 weeks and 24 months. Fourteen studies assessed fatigue, of which 9 reported statistically significant improvements (p < 0.05), particularly with Coenzyme Q10 administered for ≥12 weeks. Sixteen studies evaluated depression; vitamin D supplementation demonstrated significant reductions in depressive scores in deficient individuals (p < 0.05), while Coenzyme Q10 showed small-to-moderate improvements. Twelve studies examined cognition; most reported stabilization rather than significant improvement (p > 0.05 in several trials). Overall study quality ranged from low to moderate.

Conclusion: Coenzyme Q10 and vitamin D supplementation demonstrated modest adjunctive benefits for fatigue and depression in PD, whereas cognitive effects were primarily stabilizing. Although generally safe, current evidence remains heterogeneous, warranting larger, well-designed trials to clarify long-term efficacy and optimal dosing.