Update: studies of prepulse inhibition of startle, with particular relevance to the pathophysiology or treatment of Tourette Syndrome

Prepulse inhibition of the startle reflex (PPI) is an operational measure of sensorimotor gating, in which the motor response to an abrupt, intense stimulus is inhibited by a weak lead stimulus. PPI is reduced in several brain disorders, including Tourette Syndrome (TS); it is regulated by forebrain circuitry, including portions of the basal ganglia implicated in the pathophysiology of TS, and is also heritable and under strong genetic control. PPI has been the focus of numerous translational models, because it is expressed by most mammalian species, with remarkable conservation of response characteristics and underlying neural circuitry between rodents and primates. Several of these models have recently explored causative factors in TS - from genes to specific basal ganglia perturbations - as well as potential TS therapeutics, including novel pharmacological and neurosurgical interventions. With the focus on Comprehensive Behavioral Interventions for Tics (CBIT) in the evolving treatment model for TS, future studies might apply PPI as a predictive measure for CBIT response, or for identifying medications that might augment CBIT efficacy. In the end, a measure based on a simple pontine-based reflex will have limitations in its ability to explicate any complex behavioral phenotype.

Increased thalamic gamma band activity correlates with symptom relief following deep brain stimulation in humans with Tourette's syndrome

Tourette syndrome (TS) is an idiopathic, childhood-onset neuropsychiatric disorder, which is marked by persistent multiple motor and phonic tics. The disorder is highly disruptive and in some cases completely debilitating. For those with severe, treatment-refractory TS, deep brain stimulation (DBS) has emerged as a possible option, although its mechanism of action is not fully understood. We performed a longitudinal study of the effects of DBS on TS symptomatology while concomitantly examining neurophysiological dynamics. We present the first report of the clinical correlation between the presence of gamma band activity and decreased tic severity. Local field potential recordings from five subjects implanted in the centromedian nucleus (CM) of the thalamus revealed a temporal correlation between the power of gamma band activity and the clinical metrics of symptomatology as measured by the Yale Global Tic Severity Scale and the Modified Rush Tic Rating Scale. Additional studies utilizing short-term stimulation also produced increases in gamma power. Our results suggest that modulation of gamma band activity in both long-term and short-term DBS of the CM is a key factor in mitigating the pathophysiology associated with TS.

Randomized trial of behavior therapy for adults with Tourette syndrome

CONTEXT

Tics in Tourette syndrome begin in childhood, peak in early adolescence, and often decrease by early adulthood. However, some adult patients continue to have impairing tics. Medications for tics are often effective but can cause adverse effects. Behavior therapy may offer an alternative but has not been examined in a large-scale controlled trial in adults.

OBJECTIVE

To test the efficacy of a comprehensive behavioral intervention for tics in adults with Tourette syndrome of at least moderate severity.

DESIGN

A randomized controlled trial with posttreatment evaluations at 3 and 6 months for positive responders.

SETTING

Three outpatient research clinics.

PATIENTS

Patients (N = 122; 78 males; age range, 16-69 years) with Tourette syndrome or chronic tic disorder were recruited between December 27, 2005, and May 21, 2009.

INTERVENTIONS

Patients received 8 sessions of comprehensive behavioral intervention for tics or 8 sessions of supportive treatment for 10 weeks. Patients with a positive response were given 3 monthly booster sessions.

MAIN OUTCOME MEASURES

Total tic score on the Yale Global Tic Severity Scale and the Clinical Global Impression-Improvement scale rated by a clinician masked to treatment assignment.

RESULTS

Behavior therapy was associated with a significantly greater mean (SD) decrease on the Yale Global Tic Severity Scale (24.0 [6.47] to 17.8 [7.32]) from baseline to end point compared with the control treatment (21.8 [6.59] to 19.3 [7.40]) (P < .001; effect size = 0.57). Twenty-four of 63 patients (38.1%) were rated as much improved or very much improved on the Clinical Global Impression-Improvement scale compared with 4 of 63 (6.4%) in the control group (P < .001). Attrition was 13.9%, with no difference across groups. Patients receiving behavior therapy who were available for assessment at 6 months after treatment showed continued benefit.

CONCLUSION

Comprehensive behavior therapy is a safe and effective intervention for adults with Tourette syndrome.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00231985.

Abnormal repetitive behaviours: shared phenomenology and pathophysiology

BACKGROUND

Self-injurious behaviour (SIB) is a devastating problem observed in individuals with various neurodevelopmental disorders, including specific genetic syndromes as well as idiopathic intellectual and developmental disability. Although an increased prevalence of SIB has been documented in specific genetic mutations, little is known about the neurobiological basis of SIB. This makes vulnerability assessment and pharmacological treatment incredibly challenging.

METHOD

Here we review evidence that SIB and other repetitive, invariant behaviours, such as stereotypy, compulsions and tics, share many phenotypic similarities, are often co-morbidly expressed and have common inducing conditions. This argues for shared or overlapping pathophysiology. As much more is known about the neurobiology of these related disorders, this should make the neurobiology of SIB a more tractable problem.

RESULTS

Stereotypy, compulsions and tics are diagnostic for disorders that have received focused neurobiological investigation (autism, obsessive compulsive disorder, Tourette syndrome, respectively). In addition, animal models of these repetitive behaviours have been well characterised. Collectively, these studies have found that cortical basal ganglia circuitry dysfunction mediates repetitive behaviour. Moreover, these studies provide more detailed information and potentially testable hypotheses about specific aspects of the circuitry that may be operative in SIB.

CONCLUSIONS

We can use available information from clinical and animal models to make more precise hypotheses regarding the particular pathophysiology driving SIB. The results of testing such hypotheses should generate pharmacological strategies that may prove efficacious in reducing SIB.

Motor-cortical interaction in Gilles de la Tourette syndrome

Background

In Gilles de la Tourette syndrome (GTS) increased activation of the primary motor cortex (M1) before and during movement execution followed by increased inhibition after movement termination was reported. The present study aimed at investigating, whether this activation pattern is due to altered functional interaction between motor cortical areas.

Methodology/Principal Findings

10 GTS-patients and 10 control subjects performed a self-paced finger movement task while neuromagnetic brain activity was recorded using Magnetoencephalography (MEG). Cerebro-cerebral coherence as a measure of functional interaction was calculated. During movement preparation and execution coherence between contralateral M1 and supplementary motor area (SMA) was significantly increased at beta-frequency in GTS-patients. After movement termination no significant differences between groups were evident.

Conclusions/Significance

The present data suggest that increased M1 activation in GTS-patients might be due to increased functional interaction between SMA and M1 most likely reflecting a pathophysiological marker of GTS. The data extend previous findings of motor-cortical alterations in GTS by showing that local activation changes are associated with alterations of functional networks between premotor and primary motor areas. Interestingly enough, alterations were evident during preparation and execution of voluntary movements, which implies a general theme of increased motor-cortical interaction in GTS.

The prognosis of Tourette syndrome: implications for clinical practice

Tourette syndrome (TS) is a childhood-onset neuropsychiatric condition characterised by multiple motor and phonic tics. Comorbid behavioural problems are common, especially attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). Little is known about the long-term prognosis of TS, despite the need to inform patients about their possible clinical course and advise health care providers on clinical resource allocation strategies. This paper reviews the scientific literature on the prognosis of TS spanning the period 1990-2010. After searching three scientific databases, we identified seven original studies investigating the prognosis of TS. It is suggested that tic frequency and severity decline with age in a large proportion of patients (59-85%). Predictors of increased tic severity in adulthood include higher childhood tic severity, smaller caudate volumes and poorer fine motor control. Furthermore, the presence of untreated comorbid psychopathology, such as ADHD and OCD, can adversely affect the long-term outcome of patients with TS. Future studies on the prognosis of TS should be conducted on larger samples, both in community and clinical settings.

Compensatory neural reorganization in Tourette syndrome

Children with neurological disorders may follow unique developmental trajectories whereby they undergo compensatory neuroplastic changes in brain structure and function that help them gain control over their symptoms [1, 2, 3, 4, 5, 6]. We used behavioral and brain imaging techniques to investigate this conjecture in children with Tourette syndrome (TS). Using a behavioral task that induces high levels of intermanual conflict, we show that individuals with TS exhibit enhanced control of motor output. Then, using structural (diffusion-weighted imaging) brain imaging techniques, we demonstrate widespread differences in the white matter (WM) microstructure of the TS brain that include alterations in the corpus callosum and forceps minor (FM) WM that significantly predict tic severity in TS. Most importantly, we show that task performance for the TS group (but not for controls) is strongly predicted by the WM microstructure of the FM pathways that lead to the prefrontal cortex and by the functional magnetic resonance imaging blood oxygen level-dependent response in prefrontal areas connected by these tracts. These results provide evidence for compensatory brain reorganization that may underlie the increased self-regulation mechanisms that have been hypothesized to bring about the control of tics during adolescence.

Altered neurophysiologic response to intermittent theta burst stimulation in Tourette syndrome

BACKGROUND

The motor system in Tourette syndrome has been found to be abnormal in previous fine-motor and neurophysiologic studies.

OBJECTIVE

This novel pilot study uses repetitive transcranial magnetic stimulation as a method to characterize the neurophysiology of the motor system in Tourette syndrome.

METHOD

We investigated the modulation of cortical excitability in adult Tourette syndrome patients by measuring motor-evoked potential amplitudes before and after applying intermittent theta burst transcranial magnetic stimulation.

RESULTS

Motor-evoked potential amplitude changes over 1 and 10 minutes after intermittent theta burst transcranial magnetic stimulation were greater in 11 healthy controls than 10 adult patients with Tourette syndrome (P = 0.004).

CONCLUSIONS

This altered neurophysiologic response to intermittent theta burst stimulation may contribute to the understanding of motor cortical mechanisms in Tourette syndrome.

Deep brain stimulation in a Chinese Tourette's syndrome patient

A 31-year-old Chinese man with intractable severe, lifelong Tourette's syndrome characterised by forceful self-injurious motor tics and socially embarrassing vocal tics was treated with bilateral deep brain stimulation. Electrodes were implanted into the thalamic targets at the centromedian-parafascicular complex according to Hassler's nomenclature. A dramatic reduction of tics resulted. At 18 months postoperatively, there was an 81% improvement in his total tics count and a 58% improvement in his Yale Global Tic Severity Scale. His modified Rush video scale decreased from 13 to 8 and visual analogue scale from 10 to 3. These data show that bilateral deep brain stimulation of the thalamus can have a favourable immediate effect on severe tics in a selected group of adult patients suffering from intractable Tourette's syndrome and postoperatively the beneficial effects persisted for at least 18 months.

Altered motor network recruitment during finger tapping in boys with Tourette syndrome

In Tourette syndrome (TS), not only the tics but also the findings on deficits in motor performance indicate motor system alterations. But our knowledge about the pathophysiology of the motor system in TS is still limited. To better understand the neuronal correlates of motor performance in TS, 19 treatment-naïve boys [age 12.5 (SD 1.4) years] with TS without comorbid symptomatology were compared to an age-matched healthy control group [n = 16; age 12.9 (SD 1.6) years] in regard to brain activation during right-hand index finger tapping by means of functional magnetic resonance imaging. Group differences were found mainly in the left (contralateral) precentral gyrus, which was less activated in boys suffering from TS and in caudate nucleus as well as in medial prefrontal cortex, which was more activated compared to healthy boys. These results show that even in the first years after the onset of the disorder, an altered brain network of motor performance is recruited. These alterations in brain regions frequently associated with TS are probably based on functional changes, which are discussed in terms of early compensatory mechanisms of the motor execution network.

Tourette syndrome (TS) bears a higher rate of inflammatory complications at the implanted hardware in deep brain stimulation (DBS)

BACKGROUND

Deep brain stimulation (DBS) is a commonly performed surgical technique for the treatment of movement disorders, and recent surgical trials concerning the treatment of a wider range of disorders have recently been published. Despite DBS being non-ablative and minimally invasive, numerous complications and side effects have been recorded. In particular, concerning the growing interest in novel indications for DBS, an enthusiastic approach has put neurosurgeons at risk of underestimating some of the complications that might be associated with specific characters of the treated disease.

OBJECTIVE

Our objective was to evaluate hardware failures and rates of infective complications in correlation to the different indications to DBS, in order to ascertain whether DBS in Tourette syndrome (TS) is characterized by specific risks and pitfalls.

METHODS

We retrospectively reviewed our experience of 531 procedures on 272 patients treated for various movement disorders, among which 39 patients were treated for conservative treatmentrefractory TS.

RESULTS

A statistically significant association of infective complications was found with the TS subgroup.

CONCLUSIONS

It is our belief that specific behavioral characters of the TS patients may be put into association with this specific complication and need to be considered carefully when indicating DBS as treatment of choice for these patients.

Deep brain stimulation therapy for treatment-refractory Tourette's syndrome: A review

Tourette's syndrome is a chronic neurobehavioral disorder that can demonstrate refractoriness to conservative treatments, or to invasive nonsurgical treatments such as botulinum toxin infiltration, or to psychobehavioral treatments. In these cases, the surgical option is often proposed, either with lesional interventions, or more recently with deep brain stimulation (DBS). This latter modality is currently preferred because of its reversibility and modularity. Some relevant issues, however, still persist in terms of appropriate indication to treatment, selection of target, and follow-up evaluation.

[Surgical targets in Psychiatric disorders. From movement to emotions]

Deep brain stimulation (DBS) for psychiatric disorders refractory to conventional treatments are currently been performed based on the knowledge obtained in the motor disorder surgery and mainly in Parkinson's disease. Depression, obsessive-compulsive disorder (OCD) and Tourette syndrome, all of them are cortico-striato-thalamo-cortical pathological process involved in the limbic loop of the basal ganglia. This review describes the different targets in these pathological neuro-psychiatric disorders. For OCD there are currently two targets, ventral striatum (VS) Accumbens nucleus (Nacc) and the subthalamic nucleus (STN). In refractory depression the subgenual area (25 Brodmann area) and VS/Nacc. For Tourette syndrome the ventralis oralis internus and centromedianum/parafascicularis of the thalamus (Voi and CM/Pf) and the internal part of the globus pallidus (GPi). Currently there are no specific surgical target for each pathological disorder because clinical results reported are very similar after stimulation surgery. In other point, a selected surgical target also may improve different pathologies.

[Gilles de la Tourette-syndrome: treatment of a neuropsychiatric disorder]

The Gilles de la Tourette-Syndrome (GTS) is a tic disorder with both motor and vocal tics. A tic is an involuntary, fast, sudden und stereotyped movement or sound. According to international guidelines the therapy consists of pharmacologic, psychotherapeutic and neurosurgical approaches. Antipsychotics are the most effective pharmacotherapy. Psychotherapeutic approaches play a more subordinated role. Deep brain stimulation is experimentally applied in intractable GTS.

[Walking abnormalities in children]

Walking is a spontaneous movement termed locomotion that is promoted by activation of antigravity muscles by serotonergic (5HT) neurons. Development of antigravity activity follows 3 developmental epochs of the sleep-wake (S-W) cycle and is modulated by particular 5HT neurons in each epoch. Activation of antigravity activities occurs in the first epoch (around the age of 3 to 4 months) as restriction of atonia in rapid eye movement (REM) stage and development of circadian S-W cycle. These activities strengthen in the second epoch, with modulation of day-time sleep and induction of crawling around the age of 8 months and induction of walking by 1 year. Around the age of 1 year 6 months, absence of guarded walking and interlimb cordination is observed along with modulation of day-time sleep to once in the afternoon. Bipedal walking in upright position occurs in the third epoch, with development of a biphasic S-W cycle by the age of 4-5 years. Patients with infantile autism (IA), Rett syndrome (RTT), or Tourette syndrome (TS) show failure in the development of the first, second, or third epoch, respectively. Patients with IA fail to develop interlimb coordination; those with RTT, crawling and walking; and those with TS, walking in upright posture. Basic pathophysiology underlying these condition is failure in restricting atonia in REM stage; this induces dysfunction of the pedunculopontine nucleus and consequently dys- or hypofunction of the dopamine (DA) neurons. DA hypofunction in the developing brain, associated with compensatory upward regulation of the DA receptors causes psychobehavioral disorders in infancy (IA), failure in synaptogenesis in the frontal cortex and functional development of the motor and associate cortexes in late infancy through the basal ganglia (RTT), and failure in functional development of the prefrontal cortex through the basal ganglia (TS). Further, locomotion failure in early childhood causes failure in development of functional specialization of the cortex through the spinal stepping generator-fastigial nucleus-thalamus-cortex pathway. Early detection of locomotion failure and early adjustment of this condition through environmental factors can prevent the development of higher cortical dysfunction.

Neuropsychological functioning in children with Tourette syndrome with and without attention-deficit/hyperactivity disorder

OBJECTIVE

Neuropsychological functioning in children with Tourette syndrome (TS) has been characterized by subtle deficits in response inhibition, visual-motor integration, and fine-motor coordination. The association of these deficits with the tics of the TS versus co-occurring attention-deficit/hyperactivity disorder (ADHD) has not been well understood because of small sample sizes and lack of adequate control conditions. We examined neuropsychological functioning in relatively large and well-characterized samples of children categorized as TS, TS-plus-ADHD, ADHD, and unaffected controls.

METHOD

A total of 56 children with TS-only, 45 with TS-plus-ADHD, 64 with ADHD, and 71 healthy community control subjects were assessed on a battery of neuropsychological measures including the Connors' Continuous Performance Test (CPT), the Stroop Color-Word Interference Test (Stroop), the Beery Visual-Motor Integration Test (VMI), and the Purdue Pegboard Test.

RESULTS

There were no differences between children with TS-only and unaffected controls on the measures of response inhibition and visual-motor integration. Boys with TS-only but not girls with TS-only were impaired in the dominant hand Purdue performance. Children with ADHD were impaired on all study measures. Children with TS-plus-ADHD revealed no deficits on the Stroop, VMI, and Purdue tests but were impaired on the sustained attention portion of the CPT.

CONCLUSIONS

These results indicate that co-occurring ADHD may be responsible for the neuropsychological deficits, or at least those assessed in the present study, in children with TS. Explanations in terms of neurobiological mechanisms of co-occurring TS and ADHD, as well as possible compensatory mechanisms in children with TS, are discussed.

An update on Tourette syndrome

Recent advances in our understanding of the phenomenology, etiology, pathophysiology, and treatment of Tourette syndrome are discussed. Tourette syndrome appears to involve dysfunction of limbic and somatosensory "traffic" through the basal ganglia, within corticostriatal-thalamocortical circuits. Dynamic alterations in the balance of these inputs may dictate the manifestations (sensory, motor, affective, and behavioral) of the disorder at any given time. Individualized assessment and treatment are the keys to optimal treatment of this condition.

Neurobiological substrates of Tourette's disorder

OBJECTIVE

This article reviews the available scientific literature concerning the neurobiological substrates of Tourette's disorder (TD).

METHODS

The electronic databases of PubMed, ScienceDirect, and PsycINFO were searched for relevant studies using relevant search terms.

RESULTS

Neuropathological as well as structural and functional neuroimaging studies of TD implicate not only the sensorimotor corticostriatal circuit, but also the limbic and associative circuits as well. Preliminary evidence also points to abnormalities in the frontoparietal network that is thought to maintain adaptive online control. Evidence supporting abnormalities in dopaminergic and noradrenergic neurotransmission remains strong, although the precise mechanisms remain the subject of speculation.

CONCLUSION

Structural and functional abnormalities in multiple parallel corticostriatal circuits may underlie the behavioral manifestations of TD and related neuropsychiatric disorders over the course of development. Further longitudinal research is needed to elucidate these neurobiological substrates.

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.

Tourette's syndrome: a review from a developmental perspective

The object of this review is to summarize some of the recent developments in the understanding of Tourette's Syndrome which can be regarded as the prototype of a developmental psychopathological entity. The review covers the following topics: tics and their developmental course; sensory phenomena related to tics including measurement of these phenomena; pathophysiology of tics and compensatory phenomena and the parallel development of the various psychiatric comorbidities as they emerge over the life span. Finally there is an attempt to summarize the major points and future directions.

[Outlines of interdisciplinary addiction research given by the example of medical imaging with PET, SPECT and fMRI regarding effects of psychotropic substances]

The addiction phenomenon provides a fertile ground for the application of the tools of medical imaging which contribute to the development of scientific conceptualization of the effect of psychotropic substances. Medical imaging as for instance PET (Positron Emission Tomography), SPECT (Single Photon Emission Tomography) or functional Magnetic Resonance Imaging (fMRI) are well established for the examination of functional activity in the living brain. Medical imaging permits the development of functional activation maps during perceptual, cognitive or emotional efforts with a high temporal and spatial resolution. Medical imaging devices have therefore also been used to help our understanding of many aspects of the pharmacokinetics and pharmacodynamics of abused drugs. Because Delta-9-Tetrahydrocannabinol and cocaine continue to be the most commonly used illicit drugs, their effects on the brain function are of major interest. The cannabinoid CB(1) receptor agonist Delta(9)-THC as for instance has also been suggested for treatment of Tourette syndrome (TS). This article provides an overview of present applications of medical imaging with PET, SPECT, and fMRI and its results regarding addiction-related research on Delta-9-Tetrahydrocannabinol and cocaine.

Cognitive functioning in Tourette syndrome

Tourette Syndrome (TS) is characterized by tics, which are thought to reflect striatal dysfunction. Changes in functioning of the striatum in TS could lead to dysfunction in frontostriatal pathways involving cortical regions such as the dorsolateral prefrontal and anterior cingulate cortex. This in turn could result in deficits in specific cognitive processes and impairment on particular cognitive tasks. The aim of this review is to summarize the major findings of key studies of cognitive functioning in TS. The limitations and neurological implications of the reported findings are also discussed. Although the methodological limitations associated with many studies compel further investigation, tentative conclusions may be drawn from the available literature. While co-morbidities such as attention deficit-hyperactivity disorder (ADHD) may be associated with more significant executive dysfunction, we can conclude that patients without co-morbidities exhibit milder deficits in attention and inhibition-related processes. These cognitive difficulties are likely to reflect dysfunction with frontostriatal pathways involving the anterior cingulate circuit.

Influence of sympathetic autonomic arousal on tics: implications for a therapeutic behavioral intervention for Tourette syndrome

OBJECTIVES

The pharmacological treatment of Tourette syndrome (TS) has improved due to the application of new medications and combinations of medications, coupled to greater phenomenological and neurobiological understanding of the condition. Nevertheless, for many individuals with TS, potentially troublesome tics persist despite optimized drug treatment. Anecdotally, a relationship is frequently described between tic frequency and states of bodily arousal and/or focused attention. The galvanic skin response (GSR) is an accessible and sensitive index of sympathetic nervous activity, reflecting centrally induced changes in peripheral autonomic arousal. Sympathetic nervous arousal, measured using GSR, has been shown to have an inverse relationship with an electroencephalographic index of cortical excitability (slow cortical potential), and GSR arousal biofeedback shows promise as an adjunctive therapy in management of treatment-resistant epilepsy.

METHOD

We examined how changes in sympathetic arousal, induced using GSR biofeedback, impact on tic frequency in individuals with TS. Two different physiological states (sympathetic arousal and relaxation) were induced using GSR biofeedback in 15 individuals with a diagnosis of TS. During both biofeedback sessions, participants were videotaped to monitor the occurrence of tics.

RESULTS

We observed significantly lower tics during relaxation biofeedback compared to arousal biofeedback, with tic frequency positively correlating with sympathetic arousal during the arousal session.

CONCLUSION

These findings indicate that the conjunction of focused attention to task and reduced peripheral sympathetic tone inhibits tic expression and suggests a potential therapeutic role of biofeedback relaxation training for tic management in patients with TS.

The relationship of pineal calcification and melatonin secretion to the pathophysiology of tardive dyskinesia and tourette's syndrome

Despite current intensive research, the pathophysiology of tardive dyskinesia (TD), a serious neurological side effect of neuroleptic treatment, is poorly understood. Prompted by the observation of an increased incidence and severity of abnormal perioral movements in neuroleptic-treated pinealectomized, as compared to intact rats, we suggested that the pineal gland exerts a protective effect which mitigates against the development of TD and, by inference, that reduced melatonin secretion may be related to the pathophysiology of TD. To investigate this proposition further, we studied the association of TD with pineal calcification (PC) on CT scan in chronic schizophrenic patients. Our findings revealed a significant association between TD and PC and suggest, furthermore, that PC may be a neuroradiological marker of TD. Since PC may reflect diminished secretory activity of the gland, these findings support the hypothesis that the pathophysiology of TD is linked to disturbances of melatonin secretion. The clinical and therapeutic implications of these novel findings are discussed. In the following communication, in which we introduce the hypothesis that disturbances of 5-HT and melatonin secretion are related to the pathophysiology of TD. Subsequently, we present a series of studies which relate to the association of TD with PC. We conclude by presenting the hypothesis that disturbances in melatonin secretion may also be relevant to the pathophysiology of Tourette's syndrome.

Functional disturbances within frontostriatal circuits across multiple childhood psychopathologies

OBJECTIVE

Neuroimaging studies of healthy individuals inform us about the normative maturation of the frontostriatal circuits that subserve self-regulatory control processes. Findings from these studies can be used as a reference frame against which to compare the aberrant development of these processes in individuals across a wide range of childhood psychopathologies.

METHOD

The authors reviewed extensive neuroimaging evidence for the presence of abnormalities in frontostriatal circuits in children and adults with Tourette's syndrome and obsessive-compulsive disorder (OCD) as well as a more limited number of imaging studies of adolescents and adults with anorexia nervosa or bulimia nervosa that, together, implicate dysregulation of frontostriatal control systems in the pathogenesis of these eating disorders.

RESULTS

The presence of an impaired capacity for self-regulatory control that derives from abnormal development of frontostriatal circuits likely interacts in similar ways with normally occurring somatic sensations and motor urges, intrusive thoughts, sensations of hunger, and preoccupation with body shape and weight to contribute, respectively, to the development of the tics of Tourette's syndrome, the obsessions of OCD, the binge eating behaviors of bulimia, and the self-starvation of anorexia.

CONCLUSIONS

Analogous brain mechanisms in parallel frontostriatal circuits, or even in differing portions of the same frontostriatal circuit, may underlie the differing behavioral disturbances in these multiple disorders, although further research is needed to confirm this hypothesis.

Executive and attention functioning among children in the PANDAS subgroup

Evidence from past studies indicates that adults and children with Obsessive-Compulsive Disorder (OCD) and Tourette syndrome (TS) experience subtle neuropsychological deficits. Less is known about neuropsychological functioning of children and adolescents with a symptom course consistent with the PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infection) subgroup of OCD and tics. To provide such information, we administered three tests of attention control and two of executive function to 67 children and adolescents (ages 5-16) diagnosed with OCD and/or tics and a symptom course consistent with the PANDAS subgroup and 98 healthy volunteers (HV) matched by age, sex, and IQ. In a paired comparison of the two groups, the PANDAS subjects were less accurate than HV in a test of response suppression. Further, in a two-step linear regression analysis of the PANDAS group in which clinical variables were added stepwise into the model and in the second step matching variables (age, sex, and IQ) were added, IQ emerged as a predictor of performance on this task. In the same analysis, ADHD diagnosis and age emerged as predictors of response time in a continuous performance task. Subdividing the PANDAS group by primary psychiatric diagnosis revealed that subjects with TS or OCD with tics exhibited a longer response time compared to controls than subjects with OCD only, replicating previous findings within TS and OCD. This study demonstrates that children with PANDAS exhibit neuropsychological profiles similar to those of their primary psychiatric diagnosis.

[Deep brain stimulation in the surgical management of Tourette syndrome]

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by the presence of vocal and motor tics. Besides tics, patients with TS exhibit a variety of behavioural symptoms, particularly deficit-hyperactivity disorder and obsessive-compulsive disorder. Behavioural therapy is applied in patients with mild forms of TS but it has not been proven to be effective in the long-term follow-up. Patients with disabling motor and vocal tics are treated with neuroleptics and other agents interacting with the dopaminergic system. In most patients reaching adulthood, symptoms spontaneously decrease. Only a limited number of adult patients require long-term medication. Only those patients who were most severely disabled by tics and concomitant obsessive-compulsive disorder were treated in the past by neuroablative neurosurgical procedures. Nowadays, deep brain stimulation is applied in patients with severe forms of TS because of its safety, adjustability, and efficacy.

[Tics and Gilles de la Tourette syndrome]

INTRODUCTION

Tourette syndrome is a neurologic disorder characterized by involuntary vocal and motor tics. It affects around 1 to 2% of school-age children and is the most common movement disorder in paediatric age. Tics are involuntary or semivoluntary, sudden, brief, intermittent, repetitive movements (motor tics) or sounds (phonic tics). It is often associated with psychiatric comorbidities, mainly attention-deficit/hyperactivity disorder and obsessive-compulsive disorder. Given its diverse presentation, Tourette's syndrome can almost mimic many hyperkinetic disorders, making the diagnosis challenging at times.

DEVELOPMENT

The etiology of this syndrome is thought to be related to basal ganglia dysfunction and many clues have been pursued, both genetic and environmental factors, but no compelling major contribution to the pathogenesis of the disease has yet emerged. Treatment can be behavioural, pharmacologic, or surgical, and is dictated by the most incapacitating symptoms. Alpha-2-adrenergic agonists are the first line of pharmacologic therapy, but dopamine-receptor-blocking drugs are required for multiple, complex tics. Dopamine-receptor-blocking drugs are associated with potential side effects.

CONCLUSION

Appropriate diagnosis and treatment can substantially improve quality of life and psychosocial functioning in affected patients.

[Clinical aspects of Tourette syndrome]

Tourette syndrome (TS) is a hereditary, chronic, neurobiological disease, characterized by the presence of motor and vocal tics. The disease is often accompanied by other symptoms: Attention Deficit Hyperactive Disorder (ADHD), Obsessive Compulsive Disorder (OCD), sleeping disorders, learning disabilities, speech disfluencies, outbursts of extreme anger and behavioural problems. Treatment must be multidisciplinary. The most disabling symptom should be treated medically and the drug of first choice depends on the pathophysiology of this symptom.

[Tourette syndrome. Genetics, neuroanatomy and neurotransmitters]

The etiology and pathophysiology of Tourette syndrome (TS) have not yet been clarified. Despite inconsistencies in the literature, some conclusions can be drawn on genetics, neuroanatomy and neurotransmitters. The inheritance of TS is unknown; the etiology seems to be polygenic. The basal ganglia are probably smaller in patients with TS. A dysfunction in the dopaminergic pathway causes tics. ADHD results from a decreased concentration of dopamine and an increased concentration of noradrenaline. OCD is caused by a dysfunction in serotonin and probably dopamine.

Neurocognitive correlates of child obsessive compulsive disorder and Tourette syndrome

This study investigated the neurocognitive correlates of childhood OCD and TS, which are purported to share frontal-striatal dysfunction. Neurocognitive measures tapping frontal-striatal functions such as executive, attention/memory, and visuomotor abilities were administered to three groups of participants, OCD without comorbid TS (OCD), TS without comorbid OCD (TS), and normal controls. Results suggested that OCD group demonstrated deficits in the area of spatial attention relative to healthy controls. The OCD participants demonstrated no cognitive deficits compared to the TS group. TS participants showed trends towards impairments in the areas of response inhibition, divided attention, and cognitive flexibility relative to the OCD and normal control groups. Spatial attention deficits for the OCD group are partially consistent with adult OCD studies indicating deficits in spatial memory. TS findings were less robust and may be construed tentatively as suggestive of executive function deficits. Future research is needed to delineate the influence of development on neurocognitive deficits associated with OCD and TS.

Tourette syndrome and obsessive-compulsive disorder

Tourette syndrome and obsessive-compulsive disorder are neuropsychiatric disorders that have sparked considerable interest over the decades. They are the focus of research for a remarkable diversity of disciplines, ranging from neuroimagers and prenatal epidemiologists to experts in the neural circuits that connect the cortex with the basal ganglia, as well as neuroimmunologists focusing on brain-based autoimmune phenomena. Several hypotheses have been put forward to explain the onset and exacerbation of these illnesses. Here, we discuss the clinical phenomenology and treatment options that are currently available. New psychopharmacological agents are being used that are based on a greater understanding of the neurobiology and are being used in combination with behavioral interventions. Longitudinal clinical investigations into clinical symptoms and the natural course are providing additional clues on the underlying pathophysiology. Recent advances in research models are also reviewed in an attempt to clarify some of the molecular etiologies that lead to these disorders.

Deep brain stimulation in 18 patients with severe Gilles de la Tourette syndrome refractory to treatment: the surgery and stimulation

BACKGROUND

There have been several reports of successful deep brain stimulation (DBS) for the treatment of severe Gilles de la Tourette syndrome (GTS).

METHOD

18 cases of GTS who were resistant to at least 6 months of standard and innovative treatments, as well as to psychobehavioural techniques, underwent DBS. DBS was placed bilaterally in the centromedian-parafascicular (CM-Pfc) and ventralis oralis complex of the thalamus. Patients were evaluated after surgery, with immediate and formal assessments at least every 3 months, including "on-off" and "sham off" in the first nine patients.

RESULTS

All patients responded well to DBS, although to differing degrees. The duration of follow-up assessments ranged from 3 to 18 months. The comorbid symptoms of obsessive-compulsive behaviour, obsessive-compulsive disorder, self-injurious behaviours, anxiety and premonitory sensations decreased after treatment with DBS. There were no serious permanent adverse effects.

CONCLUSIONS

DBS is a useful and safe treatment for severe GTS. The results of ours and previous DBS reports suggest that the CM-Pfc and ventralis oralis complex of the thalamus may be a good DBS target for GTS.

[The neurobiology of Tourette syndrome]

INTRODUCTION

Tourette syndrome is a hereditary neuropsychiatric disorder that manifests as multiple chronic motor tics and verbal tics. The neurobiological disorders that seem to account for the symptoms that generate tics in these patients include alterations at three levels.

DEVELOPMENT

These levels are as follows: alterations in the thalamocortical corticostriatal pathway; dopaminergic dysfunction that leads to hyperactivity of this neurotransmitter, which generates tics; and probably an immunological alteration triggered by infection by group A beta-haemolytic streptococcus that creates autoantibodies to combat specific neuronal systems; nevertheless, further study is required in this area.

CONCLUSIONS

The aim of this paper was to review the pathophysiological mechanisms underlying the neurobiology of Tourette syndrome.

Chain reaction or time bomb: a neuropsychiatric-developmental/neurodevelopmental formulation of tourettisms, pervasive developmental disorder, and schizophreniform symptomatology associated with PANDAS

We present the case of a boy who over time sequentially exhibited symptoms consistent with a pervasive developmental disorder, schizophreniform symptomatology, multiple motor and vocal tics, and myoclonus. During this period he experienced multiple episodes of group A beta-haemolytic streptococcal (strep) infection confirmed by culture and serological studies. We speculate that paediatric autoimmune neuropsychiatric disorder associated with strep (PANDAS) may have served as an element in a complex chain of causation influencing the expression of his symptoms. Our main emphasis is to utilize our case study as an example of the application in case formulation of the neuropsychiatric developmental model and of the neurodevelopmental model on symptom ontogenesis and clinical outcome.

Malignant Tourette syndrome

The aim of this work was to draw attention to potentially life-threatening symptoms associated with Tourette syndrome (TS) and to explore their relationship to TS comorbidities. Medical records of all patients with TS evaluated at our Movement Disorders Clinic between July 2003 and July 2006 were reviewed. Data on patients with malignant TS, defined as >or=2 emergency room (ER) visits or >or=1 hospitalizations for TS symptoms or its associated behavioral comorbidities, were entered into a dataset and analyzed. Five illustrative cases are described. Of 333 TS patients evaluated during the 3-year period, 17 (5.1%) met the criteria for malignant TS. Hospital admission or ER visits were for tic-related injuries, self-injurious behavior (SIB), uncontrollable violence and temper, and suicidal ideation/attempts. Compared with patients with nonmalignant TS, those with malignant TS were significantly more likely to have a personal history of obsessive compulsive behavior/disorder (OCB/OCD), complex phonic tics, coprolalia, copropraxia, SIB, mood disorder, suicidal ideation, and poor response to medications. Although TS is rarely a disabling disorder, about 5% of patients referred to a specialty clinic have life-threatening symptoms. Malignant TS is associated with greater severity of motor symptoms and the presence of >or=2 behavioral comorbidities. OCD/OCB in particular may play a central role in malignant TS; obsessive compulsive qualities were associated with life-threatening tics, SIB, and suicidal ideation. Malignant TS is more refractory to medical treatment than nonmalignant TS.

Selective breeding for deficient sensorimotor gating is accompanied by increased perseveration in rats

Prepulse inhibition (PPI) of the acoustic startle response is a measure of sensorimotor gating that is deficient in some neuropsychiatric disorders, such as schizophrenia and Tourette's syndrome. Experimentally induced PPI deficits in rats are regarded as endophenotype to study the biological mechanisms and therapeutic strategies of these disorders. We have recently shown that selectively breeding rats for high and low PPI levels, respectively, leads to groups with different PPI performance that remains stable from the second generation on. We here tested whether the low PPI is accompanied by other behavioral deficits. Different spatial and operant learning paradigms were used to assess rats' learning and memory abilities as well as their behavioral flexibility. In the delayed alternation T-maze task the two groups did not differ in task acquisition and working memory. Rats with low PPI showed enhanced perseveration during switching between an egocentric and allocentric radial maze task. Enhanced perseveration was also found in an operant behavioral task, where different demands, i.e. a different number of lever presses for a pellet-reward, were assigned to and switched between two levers of a Skinner box. Rats with low PPI stayed longer at the ineffective lever before switching, thus being less able to adjust their behavior to changing reward values. Additionally, PPI low rats had a higher breakpoint value during a progressive ratio-schedule of reinforcement. Rats selectively bred for low PPI showed some cognitive deficits that are apparent in a number of psychiatric disorders with deficient information processing. Specifically in both, spatial and operant behavioral paradigms, PPI low rats are deteriorated in their ability to modulate behavior based upon new changing information. They may thus provide a non-pharmacological model that can be used to evaluate new therapeutic strategies ranging from pharmacological treatment to functional neurosurgery.

Disentangling the effects of Tourette syndrome and attention deficit hyperactivity disorder on cognitive and behavioral phenotypes

Eighty participants (62 males; 18 females; age range: 6-16 years) took part in the study, comprising four groups of 20 subjects each: TS-only, ADHD-only, TS+ADHD, controls. The age distributions, did not differ significantly among the four groups. The severity of symptoms, assessed by the TSGS, did not differ significantly between the two TS groups. Standardised measures were used throughout. The "cases" (i.e. TS-only, TS+ADHD, ADHD-only) were significantly different from controls on most measures of behavior. There were also differences amongst the various clinical subgroups, with, in general, TS-only participants being similar to controls with regards to both "total behavior" ratings and cognitive testing results. A diagnosis of ADHD, either or its own or in association with TS, was associated with greater maladaptive behavior and worse cognitive functioning. With regards to affective symptoms and anxiety, the three clinical groups did not differ from each other, but each of them was more affected than the control group. One finding in our study which differed from previous literature was that TS-only patients were rated as more "delinquent" than controls by their parents: possible reasons for this are discussed. Oppositional defiant disorder (ODD) was seen in a few (2,3,3 ODD patients in each clinical group), but as numbers were small no statistics were undertaken. Family histories were in accord with both TS and ADHD being genetic disorders, but sharing an overlap in only some cases. The "additive effect" hypothesis is discussed in detail in the light of our results and recent literature.

Tourette syndrome and tic disorders: a decade of progress

OBJECTIVE

This is a review of progress made in the understanding of Tourette syndrome (TS) during the past decade including models of pathogenesis, state-of-the-art assessment techniques, and treatment.

METHOD

Computerized literature searches were conducted under the key words "Tourette syndrome," "Tourette disorder," and "tics." Only references from 1996-2006 were included.

RESULTS

Studies have documented the natural history of TS and the finding that tics usually improve by the end of the second decade of life. It has also become clear that TS frequently co-occurs with attention-deficit/hyperactivity disorder), obsessive-compulsive disorder, and a range of other mood and anxiety disorders. These comorbid conditions are often the major source of impairment for the affected child. Advances have also been made in understanding the underlying neurobiology of TS using in vivo neuroimaging and neurophysiology techniques. Progress on the genetic front has been less rapid. Proper diagnosis and education (involving the affected child and his or her parents, teachers, and peers) are essential prerequisites to the successful management of children with TS. When necessary, modestly effective antitic medications are available, although intervening to treat the comorbid attention-deficit/hyperactivity disorder and/or obsessive-compulsive disorder is usually the place to start.

CONCLUSIONS

Prospective longitudinal studies and randomized clinical trials have led to the refinement of several models of pathogenesis and advanced our evidence base regarding treatment options. However, fully explanatory models are needed that would allow for more accurate prognosis and the development of targeted and efficacious treatments.

Enhanced cognitive control in Tourette Syndrome during task uncertainty

Tourette Syndrome (TS) is a developmental neurological condition that is characterised by the presence of multiple motor and one or more vocal tics. Tics are highly stereotyped repetitive behaviours that fluctuate in type, complexity and severity. TS has been linked to impaired cognitive control processes, however, a recent study (Mueller et al. in Curr Biol 16:570-573, 2006) demonstrated that young people with TS, although exhibiting chronic motor and vocal tics, nevertheless performed significantly better than a group of age-matched controls on a task that required extremely high levels of cognitive control (i.e., predictably shifting between executing pro-saccade and anti-saccade responses to a visual stimulus). As predictable task sequences allow task-related cognitive processes to commence prior to the presentation of target stimuli we examined whether the superior performance of the TS group could be replicated when task sequences were varied unpredictably. Our results confirmed that both the TS group and an age-matched control group benefited, by the same extent, when the saccade task (pro-saccade vs. anti-saccade) was pre-cued. In contrast, while the control group showed a significant decrease in performance on task switch trials relative to task repetition trials-the TS group exhibited no significant 'costs' of switching task. While task performance was modulated by response and target location shifts in the control group, these factors had less impact on the TS group's performance on task switch trials. These results confirm and extend the previous demonstration that individuals with TS exhibit paradoxically greater levels of cognitive control than healthy controls.

Neuroimaging of neuronal circuits involved in tic generation in patients with Tourette syndrome

OBJECTIVE

To identify brain regions generating tics in patients with Tourette syndrome using sleep as a baseline.

METHODS

We used [15O]H2O PET to study nine patients with Tourette syndrome and nine matched control subjects. For patients, conditions included tic release states and sleep stage 2; and for control subjects, rest states and sleep stage 2.

RESULTS

Our study showed robust activation of cerebellum, insula, thalamus, and putamen during tic release.

CONCLUSION

The network of structures involved in tics includes the activated regions and motor cortex. The prominent involvement of cerebellum and insula suggest their involvement in tic initiation and execution.

The role of abnormal neural oscillations in the pathophysiology of co-occurring Tourette syndrome and attention-deficit/hyperactivity disorder

OBJECTIVE

To examine the role of aberrant neural oscillatory activity in the pathophysiology of co-occurring Tourette Syndrome (TS) and Attention-Deficit/Hyperactivity Disorder (ADHD).

METHOD

Neural oscillations refer to periodic variations in the recording of neural activity. The temporal synchronization of oscillations represents a mechanism of neural communication implicated in normal brain functioning as well as psychopathology. We reviewed physiological, imaging, and neuropsychological evidence that tics and symptoms of ADHD may result from abnormal oscillatory activity in the brain.

RESULTS

Structural and functional abnormalities in the cortical-striatal-thalamo-cortical circuits may result in the disruption of oscillatory activity within the basal ganglia of individuals with TS and lead to transient hyperpolarization of selected thalamocortical regions. Extended to TS plus ADHD this or similar mechanisms, in turn, would lead to the dysrhythmia of particular vulnerable cortical regions and give rise to various deficits in motor control (TS + ADHD) as well as impulsivity and attention (ADHD). Compensatory systems within the prefrontal cortex could be activated and trained to modulate the misguided striatal and thalamocortical oscillations.

CONCLUSIONS

Although it is highly likely that abnormal neural oscillations have a prominent role in co-occurrence of TS + ADHD, its final relevance in this case deserves further differentiated research (i.e. oscillatory networks disentangled from other neuropsychiatric disorders).