Functional movement disorder comorbidity in Parkinson's disease: A multicenter descriptive study.

Functional neurological disorders (FND) are often seen in Neurology clinics and their co-occurrence with other neurological disorders is not uncommon. Patients with Parkinson's disease (PD) and Dementia with Lewy bodies may be more prone to develop functional comorbidity than other neurodegenerative diseases [ [1] Onofrj M. Bonanni L. Manzoli L. Thomas A. Cohort study on somatoform disorders in Parkinson disease and dementia with Lewy bodies. Neurology. 2010; 74: 1598-1606 Crossref PubMed Scopus (74) Google Scholar ], with estimated prevalence of 1.3–7% [ [2] Akkaoui M.A. Geoffroy P.A. Roze E. Degos B. Garcin B. Functional motor symptoms in Parkinson's disease and functional parkinsonism: a systematic review. J. Neuropsychiatry Clin. Neurosci. 2020; 32: 4-13 Crossref PubMed Scopus (27) Google Scholar ]. Previous studies have reported that PD with FND may be associated with more anxiety and depression, higher levodopa equivalent daily dose (LEDD), more dyskinesias, excessive use of diagnostic and therapeutic resources [ [3] Wissel B.D. Dwivedi A.K. Merola A. et al. Functional neurological disorders in Parkinson disease. J. Neurol. Neurosurg. Psychiatry. 2018; 89: 566-571 Crossref PubMed Scopus (64) Google Scholar ], and more dementia [ [1] Onofrj M. Bonanni L. Manzoli L. Thomas A. Cohort study on somatoform disorders in Parkinson disease and dementia with Lewy bodies. Neurology. 2010; 74: 1598-1606 Crossref PubMed Scopus (74) Google Scholar ]. We describe the demographic and clinical characteristics of a multicenter cohort of PD patients with functional movement disorders (FMD) and compare it with PD-only matched controls to expand the data on this complex clinical scenario.