BACKGROUND

Behavioral disinhibition has been proposed as a key mechanism in Tourette syndrome. Yet classic inhibition tasks have yielded inconsistent results, likely reflecting interference by strategies compensating for tic release.

METHODS

We examined a core inhibitory function that is immune to such interference because it suppresses movements automatically. We measured automatic motor inhibition behaviorally in 21 adults with Tourette syndrome and 21 healthy controls via the negative compatibility effect. When a motor response is activated, for example, by a subliminal prime stimulus, but execution is delayed, activation turns into inhibition, increasing reaction time and error. Diminished automatic inhibition could underlie tic release.

RESULTS

Both controls and patients showed strong automatic motor inhibition with no significant group difference. Bayesian statistics, allowing inference on the absence of effects, favored intact inhibition in patients. Our study was well powered.

CONCLUSIONS

Automatic motor inhibition in Tourette syndrome is neither impaired nor harnessed by compensation. © 2018 International Parkinson and Movement Disorder Society.