How can we better understand what makes behavioral interventions for tics work?
Community Summary of: A Test of the Behavioral Model of Tic Disorders Using a Dynamical Systems Framework
Authors of the article in the Journal of Behavior Therapy: Brianna C M Wellen, Krishnapriya Ramanujam, Mark Lavelle, Matthew R Capriotti, Jonathan Butner, Matthew J Euler, Michael B Himle
Published online: May 2024
Community summary posted on August 19, 2025
Word count: 675 (10 min)
Reading level: 11th grade
What have other studies found?
A premonitory urge is an uncomfortable feeling that many people report happens before a tic. People with tics report that urges usually increase in intensity until a tic is performed, then decrease immediately following the tic. This creates a strong urge-tic cycle.
Helping people with tics using behavioral treatments (instead of or along with medications) can be very effective. Two tested and frequently used behavioral treatments include habit reversal training (HRT) and exposure and response prevention (ERP). Although there are some differences, both treatments focus on teaching strategies to increase control over tics.
Researchers aren’t exactly sure how HRT and ERP work. Historically, they’ve thought that using skills to increase control over tics breaks the urge-tic cycle. This would happen because when the urge increases, but a tic does not occur, the urge then decreases naturally, through a process called habituation. This would then teach the brain that the tic behavior does not have to happen for the uncomfortable urge to go away. If this process were happening during treatment, we would find that urges decrease with increased control over tics. However, previous studies have found mixed results about urges decreasing.
Why does this study matter?
Previous studies have not had the statistical tools to closely examine how tic and urges change over time. Dynamical systems theory and statistical analysis can map how complex systems, like the urge-tic cycle, change over time. It maps how multiple different factors can affect each other and whether the system is at homeostasis (stable) or whether it is destabilized, which would be important for change through treatment.
In this study, examining whether tic suppression creates changes in the pattern of tics and urges might help researchers understand how HRT and ERP work. Also, we want to understand whether disrupting the strong homeostasis of the urge-tic cycle is how these treatments are working.
What happened?
Researchers tested two of the primary mechanisms thought to underlie HRT:
- tics are maintained through the strong urge-tic cycle. To test this, researchers used dynamical systems mapping to confirm other research that urges increase right before a tic happens and decrease right after.
- the urge-tic cycle is disrupted during tic suppression, resulting in urge reduction (habituation). To test this, researchers first looked at whether the homeostasis of the cycle was disrupted when people stopped their tics, and then looked at whether the urge decreased when participants stopped their tics from happening.
Eleven adults with tic disorders provided continuous urge ratings when they were instructed to tic freely (FTT) or to suppress tics (TSUP) during an HRT session.
What did this group learn?
Like in earlier studies, for 9 of the 11 participants, urges increased consistently right before tics happened. Also, for approximately half of the participants, urges decreased immediately following a tic. For participants who did not show this pattern, urges tended to decrease after a bout of tics instead of just one tic. This showed evidence that there is a strong urge-tic cycle that is likely maintaining tic symptoms, but that this pattern does not look the same for all people with tics.
For the second mechanism, researchers did not find evidence of consistent decrease in the premonitory urge for most of the participants, even when participants stopped their tics for a long period of time. They did, however, find evidence that stopping tics disrupted the homeostasis of the urge-tic cycle. This is evidence that the mechanism of action may not be urge reduction (habituation), but that stopping tics does disrupt the homeostasis of the urge-tic cycle, changing the overall dynamics of tics and urges, and setting the stage for new learning to occur through HRT.
What can our research team do next?
Additional research questions include:
If we do the same study over the course of treatment, not just in one session, does the urge start to decrease? Through HRT and ERP, does the urge-tic cycle settle into a new homeostasis, one in which there are fewer tics, when the treatment works?
How can you find out more?
