Abstract
Reward sensitivity has been suggested as one of the central pathophysiological mechanisms in Tourette disorder. However, the subjective valuation of a reward by introduction of delay has received little attention in Tourette disorder, even though it has been suggested as a trans-diagnostic feature of numerous neuropsychiatric disorders. We aimed to assess delay discounting in Tourette disorder and to identify its brain functional correlates. We evaluated delayed discounting and its brain functional correlates in a large group of 54 Tourette disorder patients and 31 healthy controls using a data-driven approach. We identified a subgroup of 29 patients with steeper reward discounting, characterised by a higher burden of impulse-control disorders and a higher level of general impulsivity compared to patients with normal behavioural performance or to controls. Reward discounting was underpinned by resting-state activity of a network comprising the orbito-frontal, cingulate, pre-supplementary motor area, temporal and insular cortices, as well as ventral striatum and hippocampus. Within this network, (i) lower connectivity of pre-supplementary motor area with ventral striatum predicted a higher impulsivity and a steeper reward discounting and (ii) a greater connectivity of pre-supplementary motor area with anterior insular cortex predicted steeper reward discounting and more severe tics. Overall, our results highlight the heterogeneity of the delayed reward processing in Tourette disorder, with steeper reward discounting being a marker of burden in impulsivity and impulse control disorders, and the pre-supplementary motor area being a hub region for the delay discounting, impulsivity and tic severity.
Highlights
Tourette disorder (TD) is a childhood-onset neurodevelopmental disorder, characterised by multiple motor and vocal tics, which are often associated with several psychiatric comorbidities.Enhanced sensitivity to reward [1], putatively resulting from hyperactivity of dopamine neurotransmission [2], was found in unmedicated patients with TD
The second was carried out on both TD adolescents and adults using a computational approach and revealed temporal discounting only for adolescents’ patients in comparison to a matched control group which was not correlated to tics severity or co-morbidities [10]. It remains unclear whether abnormal reward processing in TD spreads beyond the reinforcement learning in adults with TD, if it is associated with specific clinical features and especially what are its functional brain correlates
Rs-fMRI data were acquired with the eyes opened: the subjects were asked to fixate on a cross during the sequence acquisition, which was RESULTS Behavioural results The final sample included 54 TD patients and 31 healthy controls (HC)
Summary
Tourette disorder (TD) is a childhood-onset neurodevelopmental disorder, characterised by multiple motor and vocal tics, which are often associated with several psychiatric comorbidities. The second was carried out on both TD adolescents and adults using a computational approach and revealed temporal discounting only for adolescents’ patients in comparison to a matched control group which was not correlated to tics severity or co-morbidities [10]. It remains unclear whether abnormal reward processing in TD spreads beyond the reinforcement learning in adults with TD, if it is associated with specific clinical features and especially what are its functional brain correlates. We normalised the dataset using the flow field generated by the T1
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