Conclusions

They are the same as last year (and likely for a while to come) but worth reiterating, and consist of several simple but important questions: Why do tics tend to start at ages 5–10? Why are they more common in boys? Why do they tend to improve during sleep? Why do tics usually improve in early adulthood? How accurately can we predict outcome for an individual patient? Which patients need which treatments? Is secondary prevention possible? Hopefully future studies will address these and other important issues.

Competing interests

KJB participated in a clinical trial sponsored by Emalex Biosciences. AH received consultancy fees from Noema Pharma.

Grant information

This work was supported in part by the U.S. National Institutes of Health (NIH), grant R01 MH104030. The authors confirm that the funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.