Functional tics: Expanding the phenotypes of functional movement disorders?

Background and purpose: Until the outbreak reported during the COVID-19 pandemic, functional tics were considered to be a relatively rare clinical phenotype, as opposed to other functional movement disorders such as functional tremor and dystonia. To better characterize this phenotype, we compared the demographic and clinical characteristics of patients who developed functional tics during the pandemic and those of patients with other functional movement disorders. Methods: Data from 110 patients were collected at the same neuropsychiatry centre: 66 consecutive patients who developed functional tics without other functional motor symptoms or neurodevelopmental tics and 44 patients with a mix of functional dystonia, tremor, gait, and myoclonus. Results: Both groups were characterized by female sex preponderance (70%-80%) and (sub)acute onset of functional symptoms (similar to 80%). However, patients with functional tics had a significantly earlier age at onset of functional symptoms (21 vs. 39 years). Exposure to relevant social media content was reported by almost half of the patients with functional tics, but by none of the patients with other functional movement disorders. Comorbidity profiles were similar, with relatively high rates of anxiety/affective symptoms and other functional neurological symptoms (nonepileptic attacks). Conclusions: Patients who developed functional tics during the pandemic represent a phenotypic variant of the wider group of patients with functional movement disorders, associated with younger age at onset and influenced by pandemic-related factors, including increased exposure to specific social media content. Diagnostic protocols and treatment interventions should be tailored to address the specific features of this newly defined phenotype.

Automated summary

Functional tics were considered rare before the COVID-19 pandemic, but this study found that patients with functional tics had earlier onset of symptoms compared to other functional movement disorders. Exposure to social media content was reported in functional tics, but not in other disorders. Both groups had similar comorbidity profiles, including high rates of anxiety/affective symptoms and other functional neurological symptoms. These findings highlight the importance of tailored diagnostic and treatment approaches for patients with this newly defined phenotype.