Patients' experiences of Parkinson's disease: a qualitative study in glucocerebrosidase and idiopathic Parkinson's disease

Background Approximately 7-10% of Parkinson's disease (PD) patients carry a GBA (Glucocerebrosidase) mutation (GBA-PD patients), which may influence the disease's clinical course. Objectives This study aimed to explore the patient experience of GBA-PD and identify the most important symptoms and impacts to inform clinical trial measurement strategies. Methods Twenty PD patients (n = 15 GBA-PD; n = 5 idiopathic-PD) participated in qualitative interviews which explored concepts spontaneously reported or identified through a literature review. Telephone interviews with five expert clinicians included discussion of a preliminary conceptual model derived from literature. Verbatim transcripts were thematically analysed. Results Thirty symptoms reported by patients were categorized as motor, non-motor, and cognitive/psychiatric. Tremor (n = 13), memory loss (n = 13), rigidity/stiffness (n = 11), and speech problems (n = 11) were considered the most important and impactful symptoms by GBA-PD patients, although other symptoms were also relevant to the majority of patients. Key impacts included: sleep disturbances (n = 13), handwriting changes (n = 13), reduced social interaction (n = 12), dyskinesia (n = 10), depressed mood (n = 9), and fear of falling (n = 8). Key symptoms and impacts reported by GBA-PD patients were consistent with those reported by idiopathic-PD patients. Clinician interview results supported the patient findings, although some clinicians indicated that cognitive/psychiatric symptoms may present earlier in GBA-PD patients. The concepts emerging from the research informed updates to a conceptual model of GBA-PD patients' disease experience. Conclusions The findings provide in-depth understanding of the patient experience of GBA-PD. The findings confirm that the concepts relevant to assess in GBA-PD are consistent with those relevant to assess in idiopathic-PD; however, greater consideration of cognitive/psychiatric symptoms may be warranted in GBA-PD populations.