Objective: (i) Evaluate cognitive impulsivity in Tourette disorder (TD), (ii) identify neuronal correlates of cognitive impulsivity.

Background: TD is characterized by motor and vocal tics, but impulse control disorders are frequent co-morbidity with TD. Cognitive dimensions of impulsivity have been only partially addressed in this syndrome and previous studies on impulsivity in TD showed inconsistent results.

Method: 66 adults TD patients (37 with no medication [TD-Unmed]; 25 under medication [TD-Med]) and 33 healthy volunteers (HV) were recruited and assessed for impulsive action on 4-choice task (4CSRTT) and for impulsive choice on delay discounting task (DDT). In 4CSRTT, participants should respond on a cue. Higher numbers of premature responding indicated the propensity to an impulsive action. In DDT, participants choose between smaller immediate or larger delayed rewards, from which discounting rates “k” were calculated. Higher “k” values indicated tendency to an impulsive choice. Data were analyzed using mixed binomial model. Structural voxel-based morphometry (VBM) analysis was performed on regions of interest: the anterior cingulate gyrus, the frontal cortex, the insular, the accumbens and the caudate nuclei, all the regions known to account for cognitive impulsivity.

Results: Compared to HV, TD-Unmed showed a higher proportion of premature responses in the 4CSRTT. This propensity to impulsive action correlated with the severity of tics (measured by YGTSS/50) and with a higher signal intensity in the anterior cingulate gyrus and the accumbens nucleus. No difference was found between TD-Med and HV. In DDT, we found that TD-Med had a smaller proportion of delayed reward choices compared to HV, with no difference between TD-Unmed and HV. For all TD patients, the “k” values were correlated with a higher signal intensity in the accumbens nucleus and the insula.

Conclusion: Our findings suggest that in TD, impulsive actions and choices are underpinned by separate (anterior cingulate gyrus for 4CSRTT and insula for DDT) but partially overlapped (accumbens nucleus) limbic neuronal networks. Moreover, taking into account the behavioral performance in medicated and unmedicated patients, antipsychotics may potentially improve impulsive actions but impair impulsive choices in TD patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/distinct-neuronal-correlates-underpin-impulsive-action-and-impulsive-choice-in-tourette-disorder/