Clinical trials in late-stage Parkinson's disease.
Clinical trials in late-stage Parkinson's disease.
Where did the research take place?
The study site has not been established. Author addresses may differ from where the research occurred.
Toulouse, FR · Author affiliation
Department of Clinical Pharmacology and Neurosciences, Clinical Investigation Center CIC1436, Toulouse Parkinson Expert Centre, Toulouse NeuroToul Center of Excellence in Neurodegeneration, French NS-Park/F-CRIN Network, University of Toulouse, CHU of Toulouse, INSERM, Toulouse, France.Location evidence
PT · Author affiliation · country only
Laboratory of Clinical Pharmacology and Therapeutics, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.Location evidence
Torres Vedras, PT · Author affiliation
CNS-Campus Neurológico, Torres Vedras, Portugal.Location evidence
A plain-language reading has not been prepared for this paper yet.
Original abstract
Late-stage Parkinson's disease (LSPD) represents an under-recognized and under-studied phase of PD characterized by severe axial motor symptoms, high non-motor burden, cognitive impairment, functional dependence, and substantial caregiver involvement. Despite its major clinical and socioeconomic impact, LSPD seem to be largely excluded from clinical trials, likely due to advanced disability, mobility limitations, and the lack of appropriately adapted outcome measures.To better characterize the representation of this population in research, we conducted a systematic review of clinical trials listed in major clinical trials registries, focusing on studies that included participants with a Hoehn and Yahr stage of 4 or 5. As of January 2026, 353 registered trials allowed inclusion of individuals with LSPD; however, many of these studies applied exclusion criteria related to dementia. Most trials investigated pharmacological or rehabilitation interventions targeting axial or global motor symptoms. Among the published studies (27.8% of the total), only 30% actually enrolled participants with LSPD.Our findings confirm the limited inclusion of individuals with LSPD in clinical research. Broadening eligibility criteria, implementing decentralized or home-based trial designs, incorporating caregiver-centered outcomes, and adopting cognitively adapted assessment tools may foster a more inclusive and patient-centered research framework. Such efforts are essential to better address the needs of this growing and vulnerable population.