Prospective follow-up study of youth and adults with onset of functional tic-like behaviours during the COVID-19 pandemic.

Background And Purpose: Very little is known about the long-term prognosis of patients with functional tic-like behaviours (FTLBs). We sought to characterize the trajectory of symptom severity over a 12-month period.

Methods: Patients with FTLBs were included in our prospective longitudinal child and adult clinical tic disorder registries at the University of Calgary. Patients were prospectively evaluated 6 and 12 months after their first clinical visit. Tic inventories and severity were measured with the Yale Global Tic Severity Scale (YGTSS).

Results: Eighty-three youths and adults with FTLBs were evaluated prospectively until April 2023. Mean YGTSS total tic severity scores were high at baseline, with a mean score of 29.8 points (95% confidence interval [CI] = 27.6-32.1). Fifty-eight participants were reevaluated at 6 months, and 32 participants were reevaluated at 12 months. The YGTSS total tic severity score decreased significantly from the first clinical visit to 6 months (raw mean difference = 8.9 points, 95% CI = 5.1-12.7, p < 0.0001), and from 6 to 12 months (raw mean difference = 6.4 points, 95% CI = 0.8-12.0, p = 0.01). Multivariable linear regression demonstrated that tic severity at initial presentation and the presence of other functional neurological symptoms were associated with higher YGTSS total tic scores at 6 months, whereas younger age at baseline, receiving cognitive behavioural therapy for anxiety and/or depression, and prescription of selective serotonin reuptake inhibitors were associated with lower YGTSS total tic scores at 6 months.

Conclusions: We observed a meaningful improvement in tic severity scores in youth and adults with FTLBs over a period of 6-12 months.