Several studies have examined gender diffferences in children and adolescents with tics \citep{Larsh2023}, \citep{Larsh2024}, \citep{Nilles2023}. Gender differences in tic- and non-tic-related impairment were examined in 132 adolescents aged 13-17 years \citep{Larsh2023}. Tic- and non-tic-related impairment were higher in adolescent girls then in boys, and in girls parent-reported non-tic-related impairment was correlated with symptoms of OCD. In the second study, sex differences in tic severity by retrospectively reviewing YGTSS measures in 373 adolescents (13-17 years) before coronavirus disease 2019 (COVID-19) pandemic and during the pandemic \citep{Larsh2024}. There was no difference in tic severity between the sexes before the pandemic, but during the pandemic, girls had more severe tics than boys. \citet{Nilles2023} assessed the influence of sex and age on the phenomenology of tics by examining 203 children and adolescents with YGTSS. Both were found to affect tics; females had higher frequency and intensity of motor tics than males and it was associated with a greater impairment. Age was positively correlated with total tic severity score.
The definition of tic disorders can be challenging. \citet{Bartha2023a} included 127 patients (mean age 19.8 years) with tic disorders and 129 healthy controls (mean age 19.3 years). Showed that extra movements are common in healthy controls and therefore the diagnostic criterion of the occurrence of motor or vocal tics as described in the DSM V might be questioned. They suggest that movement patterns and temporal characteristics might be more useful in the definition of diagnostic criteria for tic disorders.