The relationship between stimulant medication and tics

Pharmacological therapy for Tourette syndrome: What medicine can do and cannot do

Tourette syndrome (TS) is a frequently observed developmental neuropsychological disorder occurring in children. The pathophysiology involves both genetic and environmental factors. In this review, clinical characteristics, pathophysiology, and treatment approaches based on the pathophysiology of TS are presented. The pathophysiology is the acceleration of developmental decrement of dopamine (DA) activity at the terminal of nigro-striatal (NS)-DA system causing DA D2 receptor up-ward regulation. Serotonergic neurons involving in development of the biphasic sleep-wake-rhythm, and locomotion may be involved. Pharmacological treatments constitute an important part in managing TS. Small dose of levodopa and aripiprazole showed the good effect controlling the tics, without side effects. Intervention with enhancing the day time activity and keeping the regular sleep-wake-rhythm, and encouraging locomotion are important. The data from Yoshiko Nomura Neurological Clinic for Children regarding the clinical features and outcomes, medication effects, and OCD and outcomes are shown. To discuss about the environmental factor, how the COVID-19 pandemic affected the TS patients is also presented.

Dual Task Performance in Children With Tourette Syndrome: Controlling for Comorbid ADHD

Dual task performance in children with Tourette Syndrome (TS) was studied. The participants were children with TS (N = 48, 40 male, 8 female), Attention Deficit Hyperactivity Disorder (ADHD; mixed types N = 44, 34 male, 10 female) and unaffected controls (N = 48, 34 male, 14 female). Eleven of the TS participants had no comorbidities (TS only) and they were compared to matched groups of participants with TS plus comorbidities (TS+), ADHD, and controls. Each participant was administered screening measures of behaviour, intelligence and verbal ability, as well as specific tests of dual task performance. Children with TS-only correctly recalled fewer digit span forward trials, and identified fewer spaceship pairs than controls under single task conditions in the SkySearch subtest of the Test of Everyday Attention for Children. However, the TS-only and control groups showed better counting performance while simultaneously searching for targets, than the TS+ and ADHD groups. Taken together, these results suggest that some previously reported cognitive deficits in children with TS are due to comorbidities, rather than to the syndrome itself.

[99mTc]TRODAT-1/[123I]IBZM SPECT studies of the dopaminergic system in Tourette syndrome

The good clinical effectiveness of dopamine depleter and receptor antagonists on tics suggests dopaminergic hyperactivity in Tourette syndrome (TS). In this case-control study of 10 TS patients and 15 age-matched healthy controls, we evaluated (i) presynaptic and postsynaptic striatal dopaminergic function using [(99m)Tc]TRODAT-1/[(123)I]IBZM single photon emission computed tomography (SPECT) and (ii) correlations between dopamine transporter (DAT)/D2 receptor binding sites and tic severity scores. Patients 1-5 were pretreated with haloperidol and were drug free for at least 3 months before SPECT imaging. Patients 6-10 were drug-naïve. We found no significant difference in DAT and D2 receptor binding sites between TS patients and healthy controls nor any association between striatal DAT or D2 receptor binding sites and tic severity assessed using the Modified Rush Videotape Rating Scale. Our findings provided no direct evidence of abnormally available striatal DAT or dopamine D2 receptors in TS. However, functional abnormalities of the dopaminergic system, e.g., alterations in the synaptic release of endogenous dopamine, cannot be completely ruled out.

Phasic dysfunction of dopamine transmission in Tourette's syndrome evaluated with 99mTc TRODAT-1 imaging

This study investigated the complex dysregulation of the dopaminergic neurotransmitter system in Tourette's syndrome (TS) patients challenged with methylphenidate (MPH). Eight drug-naïve male patients (aged 21-25 years) who met DSM-IV criteria for TS and had a mean disease severity of 25 on the Yale Global Tic Severity Scale were recruited. Brain (99m)TC TRODAT-1 dopamine transporter (DAT) single photon emission computed tomography (SPECT) was performed 5 days before, and 2 h after 10 mg of orally administered MPH. Eight age-matched healthy males served as controls. Repeated measures analysis of variance was used to measure differences in DAT-binding ratios before and after MPH challenge between the TS patients and controls. The DAT-binding ratios decreased significantly after MPH treatment in both groups. However, a significant interaction between group and MPH effects was found only in the right caudate, which was mainly due to a smaller decline of the DAT-binding ratio after MPH in the TS group than in the controls. Such a distinction was not found in the other striatal sub-regions in the two groups. No correlation, however, was observed between the tic severity score and DAT-binding ratio measured from the whole striatum or its sub-regions. The observed change in the DAT-binding ratio might indicate a functional abnormality of the dopaminergic system in the right caudate nucleus of TS patients. Future studies exploring dopamine transmission are thus needed to understand the pathophysiology of TS.

Evaluating dopamine transporter activity with 99mTc-TRODAT-1 SPECT in drug-naive Tourette's adults

OBJECTIVES

Findings on imaging of dopamine transporter (DAT) activity in patients with Tourette's syndrome remain inconclusive. The present study was carried out to observe DAT activity in patients with well-controlled Tourette's syndrome by using (99m)Tc-TRODAT-1 single photon emission computerized tomography (SPECT).

METHODS

Six drug-naive patients with Tourette's syndrome (mean age+/-SD, 21.2+/-1.5 years) were recruited. All met the criteria for Tourette's syndrome established in the DSM-IV. Seventeen age-matched and sex-matched healthy subjects served as the controls. Brain SPECT were acquired 165-195 min after administrating 740 MBq of (99m)Tc-TRODAT-1, using a double-headed camera equipped with ultra-high-resolution fan-beam collimators. The specific uptake ratio was calculated by subtracting the mean counts per pixel in the occipital cortex from the mean counts per pixel in the striatum, putamen or caudate nucleus and by dividing the result by the mean counts per pixel in the occipital cortex. Tic-severity scores were also measured and correlated with the specific uptake ratios.

RESULTS

No significant difference in DAT activity between patients with Tourette's syndrome and control subjects was found in the striatum and its sub-regions. Tic-severity scores were also not correlated with specific uptake ratios measured from the striatum and its sub-regions.

CONCLUSIONS

In conjunction with previous findings, our results suggested that functional abnormality of the dopamine system in patients with Tourette's syndrome might be evident only in its early stage. Adaptation to tic symptoms might play a role in regulating the neural system.

Developmental processes and brain imaging studies in Tourette syndrome

OBJECTIVES

It is often difficult to discern how findings of a neuroimaging study relate to the pathophysiology of an illness because imaging correlates may variously represent causes, consequences, or epiphenomena of the condition. The objective of this paper is to exemplify the complexities of interpreting neuroimaging data by reviewing anatomical and functional studies of Tourette syndrome (TS).

METHODS

Medline and Psychological Abstracts (PsycInfo) databases were searched for functional and anatomical neuroimaging studies of TS.

RESULTS

9 anatomical and 21 functional cross-sectional imaging studies of TS contributed to this review. Anatomical studies comparing TS patients to age-matched controls have found that lenticular nucleus volumes are reduced in TS adults, while caudate nucleus volumes are reduced in both adults and children with TS. In a study of the cerebral cortex, prefrontal volumes in TS adults were smaller, but in TS children were larger than in those of age-matched controls. Complementing the anatomical findings of reduced volumes of the caudate nucleus in TS, functional studies have suggested that frontal-striatal projections play an important role in the regulation of tic symptoms. The majority of functional studies to date, however, have been limited to the study of adults. These functional studies have yielded variable results that have limited generalizability to the pathophysiology of children with TS.

CONCLUSIONS

Although many of the findings in TS imaging may represent pathological causes of the disease, they may also be indicative of compensatory changes in the nervous system of TS subjects. Prospective studies of young children at risk will be necessary to help clarify the relationship between brain abnormalities and the course of the disease.

High presynaptic dopaminergic activity in children with Tourette's disorder

OBJECTIVE

Tourette's disorder is characterized by chronic fluctuating motor and vocal tics. Despite extensive investigation of the neuropathophysiology of the disorder by a wide array of methodologies, its neurobiochemical substrate is still unclear. Converging evidence, however, suggests a primary role of the dopaminergic system, particularly within the basal ganglia.

METHOD

This study examined the integrity of presynaptic dopaminergic function in children with Tourette's disorder, using positron emission tomography and the tracer [18F]fluorodopa (FDOPA). Accumulation of FDOPA in synaptic terminals, a measure of DOPA decarboxylase activity, was quantified in caudate nucleus, putamen, frontal cortex, and midbrain (i.e., substantia nigra and ventral tegmentum).

RESULTS

Subjects with Tourette's disorder showed higher FDOPA accumulation than controls in the left caudate nucleus (by 25%; p = .03) and right midbrain (by 53%; p = .08).

CONCLUSION

These findings provide evidence of dopaminergic dysfunction in children with Tourette's disorder which affects both cell nuclei and nerve terminals. Based on the known regulation of DOPA decarboxylase activity by post- and presynaptic receptors, and by extracellular dopamine concentration, abnormal activity in this enzyme may reflect deficits in a variety of functional elements of the dopamine system. The precise mechanism underlying an up-regulation of DOPA decarboxylase activity needs to be identified in future studies.

Childhood caffeine tic syndrome

OBJECTIVE

To determine whether caffeine ingestion was temporally correlated with tics in 2 healthy children.

METHODS

Two first-degree cousins were observed over a period of approximately 3 years, and the presence and absence of tics was recorded and correlated with consumption of or abstinence from caffeinated foods or beverages.

RESULTS

Appearance and disappearance of tics were closely and clearly temporally correlated with ingestion and elimination of caffeine in the cousins' diets.

CONCLUSIONS

Our observations suggest that caffeine may precipitate tics in susceptible children.

Neurobiology of Tourette syndrome

This article includes a discussion of approaches designed to determine neuroanatomic localization through the use of physical examination, electrophysiologic and neuroradiographic studies, and neuropathologic evaluations. The author reviews the anatomy, function, and biochemistry of frontal-subcortical circuits. Inferred and direct evidence that supports a disorder of frontal-subcortical circuits in Tourette syndrome is presented. Studies investigating specific neurotransmitters are reviewed.

Attention deficit hyperactivity disorder in the presence of Tourette syndrome

Increasing attention to comorbidity in Tourette syndrome has led to a search for factors that would help in the development of treatment strategies for attention deficit hyperactivity disorder. Despite arguments and some research supporting various viewpoints, it is still unclear to what extent the frequency of co-occurrence is high in Tourette syndrome. It also is unclear whether attention deficit hyperactivity disorder and obsessive-compulsive disorder are part of a spectrum with related genetic or environmental factors. One of the main difficulties is obtaining a truly representative community sample and agreeing upon the categorical boundaries. The consequences of this argument are discussed. Effective treatment of attention deficit hyperactivity disorder in the presence of tics and Tourette syndrome has undergone considerable change from an absolute contraindication of stimulants to cautious use. For those whom stimulants fail or produce unacceptable side effects, nonstimulant medications are available in increasing variety. Much more methodologically adequate research needs to be undertaken with them.

Neurosurgical treatment of Tourette's syndrome: a critical review

Some patients with Tourette's syndrome (TS) remain disabled despite conventional treatment. Recently, neurosurgical procedures have been reported to be potentially effective interventions for such intractable cases. Clinicians are now being asked to make recommendations to patients about these candidate operations. This review explores the reported experience with neurosurgical treatment of TS to assess critically the evidence regarding risks and benefits. Toward that end, the rationale for the various procedures and the relevant neuroanatomy are outlined and recommendations for patient selection and management of future cases are discussed. We reviewed all available published reports on this subject and two unpublished cases, totaling 36 patients. Although a variety of operations have been used to treat TS, there is limited evidence pertaining to the risks or benefits of any surgical procedure. Neurosurgical treatment of TS remains experimental, since there is only anecdotal experience with these operations. Furthermore, there is no compelling evidence that any neurosurgical procedure is superior to all others. If these experimental neurosurgeries are to continue, guidelines should be developed regarding patient and operation selection, and interdisciplinary assessment committees should implement such guidelines at institutions where these operations are performed. Moreover, future cases should be prospectively studied using contemporary technologies to assess lesion placement and size and validated clinical instruments to characterize patients and assess outcome, including adverse effects.

Neurochemical and some related psychopharmacological aspects of Tourette's syndrome: an update

Neurochemical investigations of Tourette's syndrome (TS) suggest that the symptoms of this disorder may be the result of an imbalance among several neurotransmitter and/or neuromodulator systems. Neurochemicals which have been studied included: catecholamines; acetylcholine; tryptophan and its metabolites; the amino acids γ-aminobutyric acid (GABA), glutamate, phenylalanine and p-tyrosine; trace amines; opioid peptides; cyclic AMP and androgenic hormones. A suitable animal model of TS would do much to advance our understanding of this disorder, and there are some interesting recent developments in this regard.

Association analysis of the dopamine D2 receptor gene in Tourette's syndrome using the haplotype relative risk method

Comings et al. [1991: JAMA 266: 1793-1800] have recently reported a highly significant association between Tourette's syndrome (TS) and a restriction fragment length polymorphism (RFLP) of the dopamine D2 receptor gene (DRD2) locus. The A1 allele of the DRD2 Taq I RFLP was present in 45% of the Tourette patients compared with 25% of controls. We tried to replicate this finding by using the haplotype relative risk (HRR) method for association analysis. This method overcomes a major problem of conventional case-control studies, where undetected ethnic differences between patients and controls may result in a false-positive finding, by using parental alleles not inherited to the proband as control alleles. Sixty-one nuclear families encompassing an affected child and parents were typed for the DRD2 Taq I polymorphism. No significant differences in DRD2 A1 allele frequency were observed between TS probands, subpopulations of probands classified according to tic severity, or parental control alleles. Our data do not support the hypothesis that the DRD2 locus may act as a modifying gene in the expression of the disorder in TS probands.

Neurobiological issues in Tourette syndrome

The Tourette syndrome (TS) represents an intriguing disorder that overlaps the clinical fields of neurology and psychiatry. Composed of a spectrum of familial, involuntary motor and vocal tics and co-morbid neuropsychological problems, this disorder has become a model for investigators interested in neurobehavioral research. Although the subject of numerous reports since Tourette's original description in 1885, over the past decade there has been a rapid expansion of knowledge pertaining to the phenomenology of tic syndromes and their associated problems, the role of genetic and environmental factors, and the underlying pathophysiology. The role of frontal-subcortical circuits, dopaminergic neurotransmission, and second messenger systems are highlighted. This report provides a framework for understanding current neurobiological issues in TS.

Abnormal dopamine uptake sites in postmortem striatum from patients with Tourette's syndrome

The dopamine hypothesis for Tourette's syndrome proposes that the disorder is pathologically related either to an excessive amount of dopamine or to supersensitive receptors. To evaluate these proposals, pre- and postsynaptic markers of dopamine metabolism were measured in postmortem striatum from three adults with the diagnosis of Tourette's syndrome. Neuronal dopamine uptake carrier sites [( 3H]mazindol binding) were significantly increased in number over control values by 37% in the caudate and by 50% in the putamen. High-pressure liquid chromatographic assays of dopamine and its primary metabolites, homovanillic acid and 3,4-dihydroxyphenylacetic acid, showed normal findings. D1 and D2 subtypes of dopaminergic receptors [( 3H]SCH 23390 and [3H]spiperone binding, respectively) showed only slight alterations, presumably due to treatment with neuroleptics. The concentration of adenosine 3',5'-monophosphate (cyclic AMP) in putamen was reduced by 23%. Our data support earlier proposals of a dopaminergic abnormality in TS, but suggest that the mechanism involves a significant alteration of uptake sites. We speculate that increases in carrier site binding indicate an enhanced dopamine innervation within the striatum.

Stimulant medication therapy in the treatment of children with attention deficit hyperactivity disorder

Despite the tremendous research advances that have increased our knowledge regarding the pharmacodynamics, clinical pharmacology, pharmacokinetics, and adverse effects of stimulant medications in the treatment of children with ADHD, our knowledge is yet incomplete. Perhaps the most central unresolved issue concerns our understanding of the pathogenesis, pathophysiology, and diagnosis of ADHD. This review has touched briefly on the controversy and confusion surrounding this issue. Although our understanding of the use of stimulant medications in this disorder is similarly incomplete, a review of the literature does allow certain conclusions to be made that are helpful to the practitioner. 1. Stimulant medications are an effective treatment modality for most children with ADHD. Short-term efficacy is well documented, and long-term outcome may be improved when stimulants are used with other therapeutic strategies. Stimulants in and of themselves are not a panacea. 2. It is impossible to predict which children will have a favorable response to stimulant medications and which children may have a placebo response. The use of individual single-blind medication trials is a practical solution to this problem and should be considered for all children who are candidates for stimulant therapy as a means for preventing overuse or inappropriate use of these medications. 3. The precise mechanism of action of stimulants is not yet completely understood, but stimulants appear to exert their therapeutic effects through their influence on multiple neurotransmitters in the catecholamine, dopamine, norepinephrine axis in the central nervous system. 4. The three major stimulants--methylphenidate, dextroamphetamine, and pemoline--appear to be equally efficacious, although methylphenidate has emerged as the most commonly used and most studied drug. Because of its potential for causing liver toxicity, pemoline has remained a second-line medication. 5. The three major stimulants appear to have somewhat different mechanisms of action so that failure of a patient to respond to one medication does not mean that he or she will not respond to another. 6. The recommended starting doses for the stimulants are 0.3 mg per kg of methylphenidate, 0.15 mg per kg of dextroamphetamine, and 37.5 mg of pemoline. There is a great deal of individual variability in dose response, so doses must be titrated for optimal effects in each child. Sustained release preparations are much more expensive than regular preparations and may be less effective. 7. There is no evidence that stimulants have any effect on ultimate adult height. 8. Although relatively uncommon, motor tics have been observed in children on stimulants, and all children on stimulants need to be carefully monitored for the development of tics. (ABSTRACT TRUNCATED AT 250 WORDS)