Neurodevelopmental versus functional tics: A controlled study

Andrea E Cavanna*, Giulia Purpura, Anna Riva, Renata Nacinovich, Stefano Seri

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

BACKGROUND: An unprecedented increase in newly developed functional tics, mainly in young females, has been reported during the COVID-19 pandemic. We set out to complement existing case series with the largest controlled study to date on the clinical phenomenology of functional tics versus neurodevelopmental tics.

METHODS: Data from 166 patients were collected at a specialist clinic for tic disorders during a three-year period overlapping with the COVID-19 pandemic (2020-2023). We compared the clinical features of patients who developed functional tics during the COVID-19 pandemic (N = 83) to patients with Tourette syndrome matched for age and gender (N = 83).

RESULTS: Female adolescents and young adults accounted for 86% of the clinical sample of patients with functional tics, who were less likely to report a family history of tic disorders than their matched controls with Tourette syndrome. Co-morbidity profiles were significantly different: anxiety and other functional neurological disorders were more strongly associated with functional tics, whereas attention-deficit and hyperactivity disorder and tic-related obsessive-compulsive behaviors co-occurred more frequently with neurodevelopmental tics. Overall, absence of tic-related obsessive-compulsive behaviors (t = 8.096; p < 0.001) and absence of a family history of tics (t = 5.111; p < 0.001) were the strongest predictors of the diagnosis of functional tics. Compared to neurodevelopmental tics, functional tics were more likely to present acutely/subacutely at a later age (21 versus 7 years), without a clear rostro-caudal progression. Coprophenomena, self-injurious behaviors, and complex clinical manifestations such as blocking tics, throwing tics, and tic attacks, were all over-represented in the functional group.

CONCLUSIONS: Our findings provide robust confirmation of both patient-related variables and tic characteristics contributing to the differential diagnosis between functional tics developed during the pandemic and neurodevelopmental tics reported by patients with Tourette syndrome.

Original languageEnglish
Article number120725
JournalJournal of the Neurological Sciences
Volume451
Early online date29 Jun 2023
DOIs
Publication statusPublished - 15 Aug 2023

Bibliographical note

Copyright © 2023 The Authors

Keywords

  • Functional neurological disorder
  • Functional tics
  • Neurodevelopmental tics
  • Tic disorder
  • Tourette syndrome

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