<unk>  is a common but underdiagnosed condition that reaches across all social, racial and ethnic groups. It is three to four times more frequent in males than in females. Observed prevalence rates are higher among children than adults because tics tend to remit or subside with maturity and a diagnosis may no longer be warranted for many adults. Up to 1% of the overall population experiences tic disorders, including chronic tics and transient (provisional or unspecified) tics in childhood. Chronic tics affect 5% of children and transient tics affect up to 20%. Most individuals with tics do not seek a diagnosis, so epidemiological studies of<unk>  "reflect a strong ascertainment bias" towards those with co-occurring conditions. The reported prevalence of<unk>  varies "according to the source, age, and sex of the sample; the ascertainment procedures; and diagnostic system", with a range reported between 0.15% and 3.0% for children and adolescents. Sukhodolsky, et al. wrote in 2017 that the best estimate of<unk>  prevalence in children was 1.4%. Both Robertson and Stern states that the prevalence in children is 1%. The prevalence of<unk>  in the general population is estimated as 0.3% to 1.0%. According to turn of the century census data, these prevalence estimates translated to half a million children in the US with<unk>  and half a million people in the UK with<unk> , although symptoms in many older individuals would be almost unrecognizable.<unk>  was once thought to be rare: in 1972, the US National Institutes of Health (NIH) believed there were fewer than 100 cases in the United States, and a 1973 registry reported only 485 cases worldwide. However, numerous studies published since 2000 have consistently demonstrated that the prevalence is much higher. Recognizing that tics may often be undiagnosed and hard to detect, newer studies use direct classroom observation and multiple informants (parents, teachers and trained observers), and therefore record more cases than older studies. As the diagnostic threshold and assessment methodology have moved towards recognition of milder cases, the estimated prevalence has increased. Because of the high male prevalence of<unk> , there is limited data on females from which conclusion about gender-based differences can be drawn; caution may be warranted in extending conclusions to females regarding the characteristics and treatment of tics based on studies of mostly males. A 2021 review stated that females may see a later peak than males in symptoms, with less remission over time, along with a higher prevalence of anxiety and mood disorders.
Tourette syndrome
Lesch–Nyhan syndrome
Conduct disorder
Tardive dyskinesia  Tardive dyskinesia  1
Autism spectrum
High-functioning autism
Oppositional defiant disorder
Klismaphilia