Time processing in children with Tourette's syndrome.
BACKGROUND
Tourette syndrome (TS) is characterized by dysfunctional connectivity between prefrontal cortex and sub-cortical structures, and altered meso-cortical and/or meso-striatal dopamine release. Since time processing is also regulated by fronto-striatal circuits and modulated by dopaminergic transmission, we hypothesized that time processing is abnormal in TS.


METHODS
We compared time processing abilities between nine children with TS-only (i.e. without major psychiatric comorbidities) and 10 age-matched healthy children, employing a time reproduction task in which subjects actively reproduce different temporal intervals, and a time comparison task in which subjects judge whether a test interval is longer or shorter than a reference interval. IQ, sustained and divided attention, and working memory were assessed in both groups using the Leiter International Performance Scale-Revised, and the Digit Span sub-test of the WISC-R.


RESULTS
Children with TS-only reproduced in an overestimated fashion over-second, but not sub-second, time intervals. The precision of over-second intervals reproduction correlated with tic severity, in that the lower the tic severity, the closer the reproduction of over-second time intervals to their real duration. Time reproduction performance did not significantly correlate with IQ, attention and working memory measures in both groups. No differences between groups were documented in the time comparison task.


CONCLUSIONS
The improvement of time processing in children with TS-only seems specific for the over-second range of intervals, consistent with an enhancement in the 'cognitively controlled' timing system, which mainly processes longer duration intervals, and depends upon dysfunctional connectivity between the basal ganglia and the dorso-lateral prefrontal cortex. The absence of between-group differences on time comparison, moreover, suggests that TS patients manifest a selective improvement of 'motor' timing abilities, rather than of perceptual time abilities. Our data also support an enhancement of cognitive control processes in TS children, probably facilitated by effortful tic suppression.
Vicario
Carmelo Mario
CM
Department of Psychology, University of RomeLa Sapienza, Rome, Italy. carmelo.vicario@uniroma1.it
Martino
Davide
D
Spata
Felice
F
Defazio
Giovanni
G
Giacchè
Roberta
R
Martino
Vito
V
Rappo
Gaetano
G
Pepi
Anna Maria
AM
Silvestri
Paola Rosaria
PR
Cardona
Francesco
F
D016022:Case-Control Studies; D002648:Child; D006801:Humans; D007100:Imitative Behavior / Q000502:physiology*; D008297:Male; D016555:Matched-Pair Analysis; D046709:Pattern Recognition, Physiological / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012016:Reference Values; D013998:Time Perception / Q000502:physiology*; D005879:Tourette Syndrome / Q000503:physiopathology* / Q000523:psychology