Disease modeling in functional movement disorders

Introduction: The mechanisms underlying functional movement disorders are poorly known. We examined whether experience of a movement disorder model in the family and/or the friendships contributes to functional movement disorders. Methods: The hypothesis was tested in a caseecontrol study including 33 patients with functional movement disorders and 66 age- and sex-matched patients with organic movement disorders and using a conditional logistic multivariable analysis (adjusted by age, education, disease duration, chronic medical illnesses and clinical phenotype). Results: Case-control comparison yielded a significant association between functional movement dis- orders and exposure to phenotypically congruent movement disorder models (Odds ratio, 3.9, p 1⁄4 0.01), mainly when disease model came from friendships (Odds ratio, 5.9, p 1⁄4 0.04). By contrast no association was found between functional movement disorders and phenotypically different neurological or non neurological disease models. A significant inverse relationship between exposure to a phenotypically concordant movement disorder model and age of disease onset was also observed. Conclusions: These findings support disease modeling as a factor contributing to the phenomenology of functional movement disorders.