Masumeh Saeidi Health Providers 2820-9192 5 1 2025 06 01 COVID-19 and the Risk of New-Onset Parkinson’s Disease and Multiple Sclerosis: A Systematic Review of the Evidence 61 81 220174 10.22034/hp.2025.518640.1063 EN Sulemana Saibu Clinical Research Directorate, Paediatric Research, GNCH, RVI, The Newcastle upon Tyne Hospitals NHS Foundation Trust 2. Institute of Applied Health Sciences, University of Aberdeen, Aberdeen, United Kingdom. 0009-0001-5136-3026 Moses James Ikpeme Senior Lecturer, Faculty of Medicine, School of Public Health, Imperial College, London, United Kingdom. 0000-0002-4685-1586 Onyinyechukwu Franscisca Akaeje Health, Safety, Environment and Quality Coordinator, Subsea 7 Sutton London, United Kingdom. Journal Article 2025 04 27 <strong><em>Background: </em></strong>Emerging evidence suggests COVID-19 may increase the risk of long-term neurological complications, including Parkinson’s disease (PD) and multiple sclerosis (MS). This review examines the potential association between COVID-19 and new-onset neurodegenerative diseases to clarify risks and guide future research and clinical care.<br /><strong><em>Materials and Methods:</em></strong> This systematic review searched multiple databases-including Medline/PubMed, Embase, PsycINFO, SciELO, Web of Science, ProQuest, Scopus, CINAHL, and the WHO COVID-19 database-as well as grey literature from January 2020 to December 2024 for studies reporting confirmed COVID-19 followed by new diagnoses of PD or MS. Two reviewers independently screened and extracted data on demographics, clinical features, diagnostics, and outcomes, assessing study quality with a standardized checklist.<br /><strong><em>Results</em></strong>: Twenty-one studies met inclusion criteria, including 18 case reports and 3 cohort studies, mostly from Europe and the Americas, with participants aged 21–76 years. Among 279,911 individuals, 0.14% developed PD and 0.007% developed MS after COVID-19 infection. Diagnoses were confirmed clinically and through imaging, often with elevated inflammatory markers or genetic predispositions. Neurological symptoms appeared from a few days to one year post-infection, including motor deficits, cognitive decline, and sensory disturbances. Proposed mechanisms involved viral neurotropism, immune dysregulation, and persistent inflammation. Most patients received disease-specific treatments, with outcomes ranging from full recovery to persistent deficits. Although study quality was generally good, the predominance of case reports and moderate certainty of evidence require cautious interpretation.<br /><strong><em>Conclusion: </em></strong>This review suggests a possible increased risk of neurodegenerative diseases such as MS and PD following COVID-19, likely linked to immune and inflammatory processes. Well-designed, large-scale longitudinal studies are essential to confirm these findings and better understand the long-term neurological consequences. https://www.health-providers.ir/article_220174_039a3e413f0e5b65cfa7475a0faa357f.pdf