Plenary lecture by James Leckman, ESCAP 2009 Budapest

TOURETTE SYNDROME: THE RELENTLESS DRUMBEAT

ESCAP 2009 Congress in Budapest, Hungary: original abstract by professor James Leckman, Yale University, The Child Study Center and the Department of Psychology and Pediatrics, New Haven, USA – “Tourette Syndrome: The Relentless Drumbeat”, Plenary Session VII., 25 August 2009, 09:00, Chaired by A. Apter (Israel).

professor James LeckmanTourette syndrome (TS) is childhood onset neurodevelopmental disorder characterized by motor and vocal tics as well as frequent comorbid attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). This presentation will begin with a brief review of the phenomenology and natural history of TS and then focus on emerging neurobiological data from postmortem and in vivo neuroimaging, electrophysiological and magnetoencephalographic (MEG) studies. Initially, we will focus on the presence of premonitory urges, the disappearance of tics during periods of goal-directed behavior, the fractal character of tics in time, and their usual partial remission over the course of adolescence. Preliminary data from postmortem brain studies indicate that some individuals with persistent TS have a loss of key subtypes parvalbumin positive GABAergic and cholinergic inter-neurons in the striatum. The affected cells are present within the Associative and Sensorimotor cortico-basal ganglia networks that are known to be fundamental to the acquisition of habits. Building on current theories concerning the hierarchical interactions of these networks in habit formation, we conclude that the volumetric MRI data (lower caudate volumes) are consistent with both the postmortem brain studies and the key role the Associative network likely plays in both habit formation and tic suppression.

Next, we conclude that the functional MRI findings also support the importance of the interaction of the Associative as well as the Sensorimotor networks in tic initiation and suppression and suggest that the Limbic network may also play a role. Similarly, preliminary electrophysiological studies of alpha coherence support the interaction of the Associative and Sensorimotor cortico-basal ganglia networks during periods of tic suppression. Preliminary data also point to this interaction being crucial to an understanding of why Habit Reversal Training is efficacious. It might also provide a basis for why tics often partially remit by early adulthood. Preliminary MEG studies point to the importance of the Sensorimotor network in understanding the thalamocortical dysrhythmias associated with tics and the potential value of the Supplementary Motor Area as a target for repetitive Transcranial Magnetic Stimulation. The current targets for Deep Brain Stimulation are also consistent with these networks being key to the emergence of tics. Finally, despite significant progress, much remains to be learned before we gain a full understanding of the complex, challenging, enigmatic, internal world that is TS.

Go to the Budapest 2009 Congress page.