Prevalence of tic disorders and Tourette syndrome in a Swedish school population

The aim of the study was to find the epidemiological distribution of tic disorders and Tourette syndrome (TS) in Swedish school children aged 7 to 15 years. A total population of 4,479 children and their parents were asked to fill in a questionnaire covering both motor and vocal tics. A three-stage procedure was used: screening, interview, and clinical investigation. Two hundred and ninety-seven children (190 males, 107 females) were found to have tics. TS, according to DSM-IV criteria, was found in 0.6% of the total population, another 0.8% had chronic motor tics, and 0.5% had chronic vocal tics. Further, 4.8% of the children had transient tics. All together 6.6% of 7- to 15-year-old children currently had or had experienced some kind tic disorder during the last year. Prevalence of different tic disorders was higher among younger children and in males, and was highly associated with school dysfunction. The prevalence of TS was higher than was previously thought but other tic disorders were more common in this childhood population.     

Epidemiological methods used in studies in the prevalence of Tourette syndrome

Tourette syndrome (TS) prevalence was studied since the early 80-ies. Its clinical course is characterised by co-occurrence of motor and vocal tics. Results of previous epidemiological studies were surprisingly divergent: the prevalence varied from 0.5 to 115 cases per 10,000 population. The disease previously recognised as extremely rare and severe is now considered as quite common, with often moderate course. Selected methods used in studies of TS prevalence and analysis of their possible impact on study results are presented. The studies were divided into 3 groups: studies of the hospitalised population, large-scale screenings and studies involving school population, basing on characteristic and size of population, methods of selection of subjects, diagnostic and screening methods used. Studies of the hospitalised population involved patients with most severe symptoms, in different age groups, different methods of final diagnosis confirmation were used. TS prevalence varied from 0.5 up to 15 cases per 10,000 population. Procedures used in large-scale screening studies made possible the elimination of potential selection bias. Large populations were studied using transparent and repetitive confirmation of diagnoses. Their validity was additionally checked in parallel validity studies. TS prevalence was in the range 4.3 to 10 cases per 10,000 population. The highest TS prevalence was obtained in studies involving schoolchildren. Data were gathered from multiple sources: from parents, teachers and children, as well as from classroom observation. Diagnoses were made by experienced clinicians. TS prevalence obtained in school population studies was between 36.2 up to 115 per 10,000 population.     

The electroencephalogram in Tourette syndrome

The electroencephalogram (EEG) was studied in 38 patients with Tourette syndrome. Psychometric tests and neurological evaluation identified patients with signs of additional central nervous system dysfunction. Thirteen patients (34%) had some EEG abnormality. In contrast to findings by other investigators, epileptiform activity was uncommon (only 2 out of 38). Most of the patients with EEG abnormalities either had other objective signs of neurological dysfunction or were taking haloperidol, a drug known to disturb the EEG.     

The genetics of Tourette syndrome

Tourette syndrome is a complex neurological disorder that usually becomes evident between 4 and 18 years of age. The disorder is characterized by chronic motor and phonic tics, often with a variety of behavioural comorbidities; in particular, attention-deficit hyperactivity disorder, obsessive-compulsive disorder, and impulse control disorder. The cause of Tourette syndrome is poorly understood. Although environmental factors are proposed to have a role, genetic factors are thought to be the primary contributors to the pathogenesis of this disorder. However, identification of the causative gene mutations or risk alleles has proved to be difficult. Early studies on the genetics of Tourette syndrome focused on multigenerational lineages and suggested Mendelian inheritance, but subsequent segregation analyses point to a more-complex inheritance pattern. A monogenic inheritance model has been proposed following the identification of rare genetic mutations associated with the Tourette syndrome phenotype. Although no specific mutations have found to directly cause Tourette syndrome, genetic findings may enable identification of the affected pathways, and could lead to the development of new treatment strategies. In this Review, we provide an overview of the genetics of Tourette syndrome and highlight how this knowledge has improved our understanding of the possible pathogenic mechanisms of this neurological disorder.     

The pharmacology of Tourette syndrome

Tourette syndrome (TS) is a chronic neuropsychiatric disorder characterised by multiple motor and vocal tics, plus associated behavioural symptoms. Tics are defined as sudden, rapid, repetitive non-rhythmic movements (motor tics) or vocalisations (vocal tics). Tics are distressing symptoms and can lead to considerable disruption to social functioning and quality of life. Converging evidence from different lines of research suggests that the pathophysiology of TS involves altered dopaminergic transmission in the cortico-striatal–thalamo-cortical circuits, along with other neurotransmitter systems. Pharmacotherapy is currently the treatment of choice in patients with moderate-to-severe tics, particularly when associated with deterioration in social, occupational or academic performance. This review will focus on the recent evidence base supporting the use of different medication classes for the treatment of tics in TS. The recent publication of the European and Canadian guidelines on the management of TS are based on experts’ consensus and highlight the need for randomised controlled trials, especially with regards to newly developed pharmacological agents.     

The prevalence and epidemiology of Gilles de la Tourette syndrome. Part 1: the epidemiological and prevalence studies

The prevalence and epidemiology of Gilles de la Tourette syndrome (GTS) are more complex than was once thought. Until fairly recently, GTS was thought to be a rare and, according to some, a psychogenically mediated disorder. Prevalence depends, at least in part, on the definition of GTS, the type of ascertainment, and epidemiological methods used. However, in dedicated specialist GTS clinics, the majority of patients were noted to have positive family histories of tics or GTS, and large, extended, multiply-affected GTS pedigrees indicated that many family members had undiagnosed tics or GTS: it was therefore realized that GTS was far from uncommon. Seven early epidemiological studies reported that GTS was uncommon or rare for a variety of reasons. More recently, however, two pilot studies and 12 large definitive studies in mainstream school and school-age youngsters in the community, using similar multistage methods, have documented remarkably consistent findings, demonstrating prevalence figures for GTS of between 0.4% and 3.8% for youngsters between the ages of 5 and 18 years. Of the 420 312 young people studied internationally, 3989 (0.949%) were diagnosed as having GTS. It is therefore suggested that a figure of 1% would be appropriate for the overall international GTS prevalence figure. There were however, “outliers” to the figure. For instance, GTS does seem to be substantially rarer in African-American people and has been reported only very rarely in sub-Saharan black African people. GTS is found in all other cultures, although to possibly differing degrees. In all cultures where GTS has been reported, the phenomenology is similar, highlighting the biological underpinnings of the disorder.     

The prevalence of primary sjögren's syndrome in a multiple sclerosis population

We used immunohistochemical studies to demonstrate that transferrin (the iron mobilization protein) and ferritin (the iron storage protein) are specifically localized in oligodendrocytes in gray and white matter of the human central nervous system. In addition, iron is also localized predominantly in oligodendrocytes. Oligodendrocytes have been well established as the cells responsible for myelin production in the central nervous system. The results of this study suggest that oligodendrocytes (or a subpopulation of oligodendrocytes) might have the additional function of mediating iron mobilization and storage in the central nervous system.     

Tourette syndrome, pimozide, and school phobia: the neuroleptic separation anxiety syndrome

The development of school phobia has been reported in some patients with Tourette syndrome treated with haloperidol. The author reports on a patient who developed school phobia on each of three trials with pimozide, a neuroleptic chemically similar to haloperidol, and proposes the term "neuroleptic separation anxiety syndrome." The syndrome is clinically indistinguishable from DSM-III criteria for school phobia (separation anxiety disorder). Tricyclic antidepressants may have a therapeutic or prophylactic effect. It is not known whether this neuroleptic side effect occurs in patients other than those with Tourette syndrome.     

The international prevalence,epidemiology, and clinical phenomenology of Tourette syndrome: A cross-cultural perspective

The overall international prevalence of Tourette syndrome (TS) is 1% in the majority of cultures of the world. Both TS and tics are certainly more obvious and may be more common in younger people. Moreover, TS is seen less frequently in some cultures. However, in all cultures where it has been reported, the phenomenology is similar, highlighting the biological underpinnings of the disorder. This article reviews the international prevalence, epidemiology, and clinical phenomenology of TS, from a cross-cultural perspective.     

Hallervorden-Spatz syndrome resembling a typical Tourette syndrome.

A young man presenting with a Tourette syndrome-like disorder that was the main clinical manifestation of Hallervorden-Spatz syndrome is described. It is recommended that, even in the case of slow progression, HSS should be considered in the differential diagnosis of TS-like disorders.     

The international prevalence, epidemiology, and clinical phenomenology of Tourette syndrome: A cross-cultural perspective

The overall international prevalence of Tourette syndrome (TS) is 1% in the majority of cultures of the world. Both TS and tics are certainly more obvious and may be more common in younger people. Moreover, TS is seen less frequently in some cultures. However, in all cultures where it has been reported, the phenomenology is similar, highlighting the biological underpinnings of the disorder. This article reviews the international prevalence, epidemiology, and clinical phenomenology of TS, from a cross-cultural perspective.     

Eyemovement abnormalities in a case of Tourette syndrome

Tourette syndrome (TS) is a neuropsychiatric disorder that is characterised by the presence of multiple vocal, facial, and motor tics which change with time, and a number of other behavioural phenomena. Previous studies have not revealed any ocular-motor abnormalities. We report the eye movement studies of a patient with TS, using electro-oculography and simultaneous video recording. Intrusive saccades occurred during smooth pursuit and optokinetic nystagmus. Reflexive and voluntary saccades were dysmetric and there was a complete failure of antisaccades. These abnormalities are characteristic of disease of the frontal lobes and basal ganglia. We review the literature with respect to the eye movement abnormalities associated with TS.     

The natural history of Tourette syndrome: a follow-up study

Initial reports described Tourette syndrome as a lifelong disorder. Since then, others have noted that some patients experience remissions during late adolescence. To examine this issue, we sent questionnaires to 99 patients with Tourette syndrome who were 15 to 25 years old. The majority of the 58 respondents indicated that they had fewer tics as they reached late adolescence or young adulthood. Although most reported associated behavior or learning problems, the majority felt they were coping well. The long-term outcome in many patients with Tourette syndrome may be more optimistic than previously reported.     

Tourette syndrome and dopaminergic genes: a family-based association study in the French Canadian founder population

Tourette syndrome (TS) is a genetically complex disorder for which no causative genes have been unequivocally identified. Nevertheless, a number of molecular genetic studies have investigated several candidate genes, particularly those implicated in dopamine modulation. The results of these studies were inconclusive, which may be due, at least in part, to the variable ethnicity of the patients included in different studies and the chosen research design. In this study, we used a family-based association approach to investigate the implication of dopamine-related candidate genes, which had been previously reported as possibly associated with TS [genes that encode for the dopamine receptors DRD2, DRD3 and DRD4, the dopamine transporter 1 (SLC6A3) and the monoamine oxidase-A (MAO-A). The studied group was composed of 110 TS patients. These patients were selected from the French Canadian population, which displays a founder effect. Excess transmission of the 7-repeat allele of the DRD4 exon-3 VNTR polymorphism (chi(2) TDT =4.93, 1 df, P=0.026) and the putative 'high-activity' alleles of the MAO-A promoter VNTR polymorphism (chi(2) TDT =7.124, 1 df P=0.0076) were observed. These results were confirmed in a subgroup of patients with no attention deficit/hyperactivity or obsessive compulsive comorbid disorders. Haplotype analysis using one or two supplemental polymorphism in each of these genes confirmed these associations and allowed one to identify risk haplotypes. No associations were found for DRD2, DRD3 or SLC6A3. These data support the notion that DRD4 and MOA-A genes may confer an increased risk for developing TS in the French Canadian population.     

Tourette Syndrome and social functioning in a Canadian population

Two hundred and ten patients with Tourette Syndrome (TS) and/or their parents completed a survey, answering questions about the frequency and disruptiveness of vocal and motor tics, behaviour problems and sleep disturbances. Respondents also rated the impact of TS symptoms on social relationships and level of personal and social functioning. Motor tics were reported to be more problematic than were vocal tics. Disruptive behavioural problems included obsessive-compulsive rituals, hyperactivity, anxiety, temper tantrums, mood swings, aggressiveness and coprolalia. Respondents also reported problems getting to sleep, bad dreams, somnambulism and enuresis. More than 40% of respondents reported problems in dating, and problems in making and keeping friends. Family members, friends and physicians were reported to be the most understanding and tolerant of TS symptoms; employers were rated as being the least understanding. More than 30% of respondents reported some problems in coping, but more than 50% of respondents also rated their mental health as good or excellent.