Tamara Pringsheim

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.