Tourette syndrome: clinical characteristics and current management strategies

Pimozide Alleviates Hyperglycemia in Diet-Induced Obesity by Inhibiting Skeletal Muscle Ketone Oxidation

Perturbations in carbohydrate, lipid, and protein metabolism contribute to obesity-induced type 2 diabetes (T2D), though whether alterations in ketone body metabolism influence T2D pathology is unknown. We report here that activity of the rate-limiting enzyme for ketone body oxidation, succinyl-CoA:3-ketoacid-CoA transferase (SCOT/Oxct1), is increased in muscles of obese mice. We also found that the diphenylbutylpiperidine pimozide, which is approved to suppress tics in individuals with Tourette syndrome, is a SCOT antagonist. Pimozide treatment reversed obesity-induced hyperglycemia in mice, which was phenocopied in mice with muscle-specific Oxct1/SCOT deficiency. These actions were dependent on pyruvate dehydrogenase (PDH/Pdha1) activity, the rate-limiting enzyme of glucose oxidation, as pimozide failed to alleviate hyperglycemia in obese mice with a muscle-specific Pdha1/PDH deficiency. This work defines a fundamental contribution of enhanced ketone body oxidation to the pathology of obesity-induced T2D, while suggesting pharmacological SCOT inhibition as a new class of anti-diabetes therapy.

Rats overexpressing the dopamine transporter display behavioral and neurobiological abnormalities with relevance to repetitive disorders

The dopamine transporter (DAT) plays a pivotal role in maintaining optimal dopamine signaling. DAT-overactivity has been linked to various neuropsychiatric disorders yet so far the direct pathological consequences of it has not been fully assessed. We here generated a transgenic rat model that via pronuclear microinjection overexpresses the DAT gene. Our results demonstrate that DAT-overexpression induces multiple neurobiological effects that exceeded the expected alterations in the corticostriatal dopamine system. Furthermore, transgenic rats specifically exhibited behavioral and pharmaco-therapeutic profiles phenotypic of repetitive disorders. Together our findings suggest that the DAT rat model will constitute a valuable tool for further investigations into the pathological influence of DAT overexpression on neural systems relevant to neuropsychiatric disorders.

Clinical pharmacology of dopamine-modulating agents in Tourette's syndrome

Forty years of research and clinical practice have proved dopamine (DA) receptor antagonists to be effective agents in the treatment of Tourette's syndrome (TS), allowing a significant tic reduction of about 70%. Their main effect seems to be mediated by the blockade of the striatal DA-D2 receptors. Various typical and atypical agents are available and there is still discord between experts about which of them should be considered as first choice. In addition, there are suggestions to use DA receptor agonists such as pergolide or non-DA-modulating agents. The present chapter is focusing on the clinical pharmacology of DA-modulating agents in the treatment of TS. The introduction outlines their clinical relevance and touches on the hypotheses of the role of DA in the pathophysiology of TS. Subsequently, general information about the mechanisms of action and adverse effects are provided. The central part of the chapter forms a systematic review of all DA-modulating agents used in the treatment of TS, including an overview of studies on their effectiveness, and a critical discussion of their specific adverse effects. The present chapter closes with a summary of the body of evidence and a description of the resulting recommendations for the pharmacological treatment of TS.

Guanfacine extended release as adjunctive therapy to psychostimulants in children and adolescents with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a common neurobehavioral disorder associated with a wide range of impairments. Psychostimulants are generally first-line pharmacotherapy, but symptom improvement is suboptimal in some patients. In these patients, clinicians frequently use a combination of psychostimulants and nonscheduled medications to manage ADHD, although published evidence supporting this practice was relatively scarce until recently.Guanfacine extended release (GXR), a selective alpha2A-adrenoceptor agonist, is approved as a monotherapy and adjunctive therapy to psychostimulant medications for ADHD in patients 6-17 years of age. Drug-drug interaction studies have demonstrated that the adjunctive administration of GXR with a long-acting methylphenidate preparation or lisdexamfetamine dimesylate did not change exposure to the active components of either medication in a clinically meaningful way compared with either treatment alone.Data supporting the potential efficacy of GXR adjunctive to psychostimulants were preliminarily observed in a 9-week, open-label, dose-escalation study and subsequent extension study (≤ 24 months) in subjects aged 6-17 years with suboptimal control of ADHD symptoms on psychostimulant monotherapy. In a subsequent 9-week, randomized, double-blind, placebocontrolled study of subjects aged 6-17 years with suboptimal response to a long-acting, extendedrelease, oral psychostimulant, adjunctive GXR (administered in the morning or evening) was associated with significantly greater symptom reduction than placebo and psychostimulant (ADHD Rating Scale IV [ADHD-RS-IV] total score, placebo-adjusted least squares mean reductions: GXR AM, -4.5, P = 0.002; GXR PM, -5.3, P < 0.001, based on Dunnett's test). Across multiple studies, the safety and tolerability profile of GXR administered adjunctively to psychostimulants has been consistent with the known profiles of each medication. Additional studies should further explore the role of adjunctive GXR in clinical practice to help identify those patients most likely to benefit from such therapy.

Cortical and hippocampal EEG effects of neurotransmitter agonists in spontaneously hypertensive vs. kainate-treated rats

To analyze mediatory mechanisms underlying attention-deficit hyperactivity disorder (ADHD) and their association with epilepsy, the electroencephalogram (EEG) responses to various centrally applied neurotransmitter agonists were studied in spontaneously hypertensive (SH), kainate-treated (KA), and normotensive (control) rats, with chronically implanted electrodes into the frontal cortex and hippocampus and a cannula into the lateral cerebral ventricle. In SH rats, the baseline EEG showed increased delta and beta2 activity in the hippocampus and decreased alpha/beta1 activity in both brain areas. In KA rats, these delta and alpha/beta1 effects were observed 2 weeks post-kainate, while the beta2 activity increase occurred after 5 weeks in the hippocampus and, to a greater extent, 9 weeks post-injection in both brain areas. In SH rats, NMDA increased delta and decreased alpha/beta1 activity, similar to KA rats 5 weeks post-injection. In SH rats, clonidine augmented theta/beta2 increase in the cortex and alpha suppression in both brain areas, in parallel with induction of beta2 activity in the hippocampus. These beta2 effects were observed 5 and 9 weeks post-kainate. In SH rats, baclofen produced robust delta/theta enhancement and alpha/beta1 suppression in both brain areas, with additional beta2 activity increase in the hippocampus, while muscimol was ineffective in both groups of rats. In KA rats, EEG responses to GABA agonists were similar to those in control. Our results demonstrate sensitization of NMDA receptors and α2-adrenoceptors both in SH and KA rats and that of GABAb receptors specifically in SH rats.

[The benzamides tiapride, sulpiride, and amisulpride in treatment for Tourette's syndrome]

The treatment of Tourette's syndrome is a challenge. Dopamine receptor antagonists are the drugs of first choice for the treatment of tics. Because large controlled trials are lacking, there is no consensus about which of the different neuroleptic drugs should be preferred. In Germany, tiapride seems to be used most often for the treatment of tics in children - although only one small controlled trial has been performed on it till now. In adults, other dopamine receptor antagonists such as risperidone, pimozide, and sulpiride seem to be more effective than tiapride. Today it is unknown whether new atypical neuroleptic drugs including the benzamide amisulpride are more effective than the older benzamides tiapride and sulpiride.

[Prescription of psychotropic drugs in paediatry: approved indications and therapeutic perspectives]

In France, psychotropic drugs may be classified in four categories according to their official data. The first category corresponds to psychotropic drugs with an approved indication available in paediatry. Theyare old agents (e.g. haloperidol, amitriptyline, benzodiazepines...) with the exception of methylphenidate (hyperactivity). The second one corresponds to pharmacological agents approved for some indications obtained with adults but not for a1l (i.e. restricted indication: e.g. sertraline approved in paediatry only for OCD but not for depression, risperidone approved only for the treatment of disruptive behaviors in children with subaverage IQs). For the third category, the psychotropic agent is either contraindicated or unadvised under the age of 15 or 18 years, by lack of data (e.g. most of SSRI or atypical antipsychotic drugs). For the last category, official data available in brief summaries offer no information on paediatric use and consequently their administration does not appear possible. Up to now, no approved use has been delivered to injection route (IM or IV) in France, except for an IM formulation of zuclopenthixol. Prescribing psychotropic drug has to respect good practices including close psychological and somatic monitoring that associates the young patient and his relative (psycho-education program). Particular key-points should be taken into consideration (i.e. pharmacokinetic and physiological specificities, risk of false passage under the age of 6 years with capsules or tablets, presence of alcohol in some oral solution or bitter aroma...). Beside these official data, many studies have been published but must be carefully interpreted according to their level of pertinence. Meta-analysis gather all randomised controlled trials published or not, analyse their specific pertinence and thus provide clinically relevant elements. Randomised controlled trials present clinical interest but key-points in study design must be checked (e.g. number of patients, inclusion and exclusion criteria, length of the study and clinical relevance of clinical scales...). Other studies like open trials or clinical cases do not offersufficient guarantees. Some randomised controlled trials of clinical relevance have been carried out in this population with new pharmacological classes (eg SSRI, atypical antipsychotic drugs) and may lead to extended indications in children and adolescents. According to bibliographic and official data, the main criteria in the prescribing choice may take into consideration the following sis stressing a poor benefit/risk ratio. SSRI may offer better prospects but their use has not been approved in this indication, until now. In OCD, sertraline shows great interest to enhance clinical response and represents the molecule of reference. No drug has been approved for mood disorders in children or adolescent, in France, contrary to USA where lithium can be administered over the age of 12 years. In addition, antiepileptic drugs like carbamazepine or divalproate have conducted to clinical improvement in some studies. Benzodiazepines, hydroxyzine and meprobamate use should be strictly restricted in case of anxiety symptoms but are the only agents approved in this indication despise promising results obtained with SSRI. Transitory insomnia may take advantage of alimemazine prescription (approved use over the age of 36 months). Some typical neuroleptics are indicated in tics or in behaviour disorders associated to autism or related syndromes but present clinical limitations and poor tolerability. Promising clinical trials (randomised or not) have been conducted with new atypical antipsychotic drugs like risperidone. In conclusion, present data available for paediatric use of psychotropic agents emphasizes that safety and effectiveness are not always well established in particular for the treatment of chronic disorders (long term tolerability assessment). Moreover, studies should be carried out to specify factors promoting adherence and quality of life for this young population in order to optimise clinical benefit of drug prescription.

Tic disorders: from pathophysiology to treatment

Tic disorders are stereotypic behaviours,more frequent than once believed, and therefore likely to be encountered by primary care physicians. Tics usually begin in childhood and are the clinical hallmark of Tourette Syndrome (TS), the most common cause of tics. TS is a relatively common neurobehavioural disorder with a spectrum of manifestations that wax and wane during its natural course. The pathophysiology of tics, at molecular and cellular level, is still unknown,whereas structural and functional neuroimaging studies have shown the involvement of the basal ganglia and related cortico-striato-thalamo-cortical circuits, and the dopaminergic neuronal system. Moreover, TS has a strong genetic background. The management of TS is often complicated by the presence of attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, and other behaviour disorders. The correct diagnosis is a fundamental step for a proper management of these disorders, and a multimodal treatment is usually indicated. This approach includes educational and supportive interventions, as well as pharmacological treatments when tics are at their worst.

[Central dopaminergic receptors (Part II): pathophysiological and therapeutic considerations]

The five subtypes of dopaminergic receptors exhibit different transduction, cerebral localization, regulation, pharmacological, and physiological roles, explaining their multiple pathophysiological implications in different neuropsychiatric conditions which result, at least in part from anomalous dopaminergic neurotransmission: Parkinson's disease, schizophrenia, addiction, migraine, mode disorders, Gilles de la Tourette disease, hyperactivity syndrome with attention deficit. The wide range of pharmacological implications explains the diversity of the therapeutic approaches perspectives for development of new drugs for these neuropsychiatric conditions.

Case study: severe self-injurious behavior in comorbid Tourette's disorder and OCD

This case report describes the successful treatment of severe self-injurious behavior in a 16-year-old adolescent with Tourette's disorder and obsessive-compulsive disorder. Treatment is described from initial presentation to the emergency department for severe self-inflicted oral lacerations through discharge from the inpatient psychiatric service. Modes of treatment included emergent medical intervention, intensive care services, psychopharmacology, and psychological services. The collection of treatment modalities implemented by this multidisciplinary team may serve as a guide to other health care professionals when severe self-injurious behavior is the presenting problem.

Use of the "inverse neuroleptic" metoclopramide in Tourette syndrome: an open case series

Neuroleptics are generally highly effective in suppressing tics, but their many adverse effects limit their usefulness. Animal studies have shown that, compared with both typical and atypical neuroleptics, metoclopramide has effects that are regionally circumscribed to rat motor striatum. Based on this observation and two prior case reports, metoclopramide was openly prescribed and individually titrated to diminish tics in 10 patients with Tourette syndrome. All patients improved on the Yale Global Tic Severity Scale by an average of 55%. Although we did not observe frank extrapyramidal symptoms, including tardive dyskinesia, these data are not sufficient to support clinical recommendations because of many limitations, including the absence of systematic ratings of nontic abnormal movements. However, controlled clinical studies and additional basic investigations of metoclopramide are warranted.

Stuttering: a dynamic motor control disorder

The purpose of this review is to determine what neural mechanisms may be dysfunctional in stuttering. Three sources of evidence are reviewed. First, studies of dynamic inter-relationships among brain regions during normal speech and in persons who stutter (PWS) suggest that the timing of neural activity in different regions may be abnormal in PWS. Second, the brain lesions associated with acquired stuttering are reviewed. These indicate that in a high percentage of cases, the primary speech and language regions are not affected but lesions involve other structures, such as the basal ganglia, which may modulate the primary speech and language regions. Third, to characterize the motor control disorder in stuttering, similarities and differences from focal dystonias such as spasmodic dysphonia (SD) and Tourette's syndrome (TS) are reviewed. This review indicates that the central control abnormalities in stuttering are not due to disturbance in one particular brain region but rather a system dysfunction that interferes with rapid and dynamic speech processing for production.

EDUCATIONAL OBJECTIVES

The reader will be able to describe: (1) the similarities and differences between stuttering and other speech motor control disorders, (2) which brain lesions are most likely to produce acquired stuttering in adults, and (3) what type of brain abnormality most likely underlies stuttering.

The treatment of Tourette's syndrome: current opinions

Correct education of the patient is one of the most important aspects in the treatment of Tourette's syndrome. Pharmacotherapy is often unsatisfactory and therefore should be limited to those patients who are significantly impaired. Therapy must be individualised and the most troublesome symptom should be targeted first. In the treatment of tics, dopamine receptor blocking agents are currently the most effective drugs. It is currently unknown whether classic neuroleptics, such as pimozide, selective dopamine receptor antagonists, such as sulpiride, or newer atypical antipsychotics, such as risperidone, have the best adverse effect profile. Tiapride can be used as an alternative, particularly in children. Selective serotonin-re-uptake inhibitors are recommended for the treatment of obsessive-compulsive behaviour. In children suffering from attention deficit hyperactivity disorder, psychostimulants, such as methylphenidate, are the treatment of choice. Recent studies have provided increasing evidence that stimulants do not cause a significant increase in tics in the majority of patients.