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Implicit sequence learning in young people with Tourette syndrome with and without co-occurring attention-deficit/hyperactivity disorder (ADHD)

Shephard, Elizabeth; Groom, Madeleine J.; Jackson, Georgina M.


Elizabeth Shephard

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Professor of Cognitive Neuropsychology


Impaired habit-learning has been proposed to underlie the tic symptoms of Tourette syndrome (TS). However, accounts differ in terms of how habit-learning is altered in TS, with some authors proposing habit-formation is impaired due to a deficient “chunking” mechanism, and others proposing habit-learning is over-active and tics reflect hyper-learned behaviours. Attention-deficit/hyperactivity disorder (ADHD) frequently co-occurs with TS and is known to affect cognitive function in young people with co-occurring TS and ADHD (TS+ADHD). It is unclear, however, how co-occurring ADHD symptoms affect habit-learning in TS. In this study, we investigated whether young people with TS would show deficient or hyper-active habit-learning, and assessed the effects of co-occurring ADHD symptoms on habit-learning in TS. Participants aged 9-17 years with TS (n = 18), TS+ADHD (n = 17), ADHD (n = 13) and typical development (n = 20) completed a motor sequence-learning task to assess habit-learning. We used a 2 (TS-yes, TS-no) x 2 (ADHD-yes, ADHD-no) factorial analysis to test the effects of TS, ADHD, and their interaction on accuracy and reaction time indices of sequence-learning. TS was associated with intact sequence-learning, but a tendency for difficulty transitioning from sequenced to non-sequenced performance was suggestive of hyper-learning. ADHD was associated with significantly poorer accuracy during acquisition of the sequence, indicative of impaired habit-learning. There were no interactions between the TS and ADHD factors, indicating young people with TS+ADHD showed both TS- and ADHD-related atypicalities in habit-learning.


Shephard, E., Groom, M. J., & Jackson, G. M. (2019). Implicit sequence learning in young people with Tourette syndrome with and without co-occurring attention-deficit/hyperactivity disorder (ADHD). Journal of Neuropsychology, 13(3), 529-549.

Journal Article Type Article
Acceptance Date Jun 18, 2018
Online Publication Date Jul 4, 2018
Publication Date 2019-09
Deposit Date Jun 26, 2018
Publicly Available Date Jul 5, 2019
Journal Journal of Neuropsychology
Print ISSN 1748-6645
Electronic ISSN 1748-6653
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 13
Issue 3
Pages 529-549
Keywords habit-learning, Tourette syndrome, ADHD, sequence learning, tics, comorbidity
Public URL
Publisher URL
Additional Information This is the peer reviewed version of the following article,, which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.


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