Background to Tic Disorders

Tics are involuntary movements of the body (motor tics) or the phonic system (resulting in vocal tics) that are sudden, rapid, recurrent, non-rhythmic, and stereotyped (Jankovic, Reference Jankovic1997). Tics can occur for a brief period in a child's life but then completely remit (sometimes called ‘developmental tics’, but referred to as provisional tic disorder in the Diagnostic and Statistical Manual of Mental Disorders 5th ed. [DSM-5], due to be released in May 2013; American Psychiatric Association [APA], 2012) — or may persist. When motor or vocal tics, but not both, continue for over one year, this is referred to as a chronic tic disorder; when motor and vocal tics co-occur for over one year, this indicates Tourette's disorder (more commonly known as Tourette syndrome).

The proposed diagnostic criteria for Tourette syndrome in the DSM-5 (APA, 2012), which contains some minor modifications from the criteria utilised in the DSM-IV-TR (APA, 2000; cf. Walkup, Ferrão, Leckman, Stein, & Singer, Reference Walkup, Ferrão, Leckman, Stein and Singer2010), are as follows:

1. A Both multiple motor and one or more vocal tics are present at some time during the illness, although not necessarily concurrently.

2. B The tics may wax and wane in frequency but have persisted for more than 1 year since first tic onset.

3. C The onset is before 18 years of age.

4. D The disturbance is not due to the direct physiological effects of a substance or a general medical condition.

Common simple motor tics involve the eyes (e.g., eye blinking, eye rolling), face (e.g., nose twitching, grimacing), neck (jerking) and shoulders (shrugging). These can be embarrassing or even painful for the individual (e.g., jaw snapping), and are easily distinguished from muscular twitches (fasciculations), for example, of the eyelid or lip. Complex motor tics may involve either a cluster of simple motor tics or a more coordinated sequence of movements, but these are still rapid or abrupt. Complex motor tics include licking, hitting, jumping, smelling, spitting, squatting, abnormalities of gait, forced touching, kissing self or others, and socially inappropriate comments. Complex tics can appear purposeful and may greatly impair functioning in the classroom.

Vocal tics can also be grouped into ‘simple’ and ‘complex’ categories. Simple vocal tics include throat clearing, sniffing, grunting, coughing, barking, snorting, humming, clicking and low- or high-pitched noises. Conversely, complex vocal tics typically comprise linguistically meaningful utterances such as words and phrases, interruptions in the flow of speech, and sudden alterations in pitch and volume (Eapen & Sachdev, Reference Eapen and Sachdev2008). The uttering of obscenities (coprolalia) or making of obscene gestures (copropraxia) remain among the most well-known TS symptoms. Contrary to popular belief, these tics occur in only 5–30% of individuals with TS; however, when present they can be disabling, as well as confronting and disruptive to others. Thus, the range of symptoms and presentations in individuals with tic disorders can be substantial. See Table 1 for additional examples of motor and vocal tics and related behaviours in tic disorders.

TABLE 1 Tics and Related Behaviours Commonly Encountered in Tourette Syndrome

It is worth noting that involuntary movements are present in several neurological conditions (e.g., Sydenham's chorea; Huntington's disease). However, the characteristics of a tic that separate it from other involuntary movements include the waxing and waning course; one type of tic being replaced by another; voluntary suppression (even if this is for only brief periods); and the fact that the tic is preceded by an ‘inner urge’ and in some cases a premonitory somatic sensation, such as an itch, stretch, or tightness at the site, and the movement or noise is reported to occur in response to this urge. Ironically, the ability of people with tic disorders to voluntarily suppress or postpone responding to this urge with a tic, although at the expense of mounting inner tension, can lead to misinterpretation by others that tics are under voluntary control (Eapen & Sachdev, Reference Eapen and Sachdev2008). Voluntary suppression of tics for a period of time may be associated with a later ‘rebound’ effect of increase in the occurrence of tics. This, in turn, can sometimes lead to conflict, as the person is viewed as deliberately doing it or not trying enough to stop the tic (Eapen & Črnčec, Reference Eapen and Črnčec2009).

Tic Disorders and Associated Psychiatric Comorbidity

It has been frequently observed that for children and adults with tic disorders, psychiatric comorbidity is the rule rather than the exception, with around 80% of people with tic disorders affected by comorbid conditions across the life span (Freeman et al., Reference Freeman, Fast, Burd, Kerbeshian, Robertson and Sandor2000).

Foremost among these comorbidities is attention-deficit/hyperactivity disorder (ADHD). Epidemiological studies indicate that ADHD co-occurs with TS (TS+ADHD) in around 50–60% of individuals with TS, higher still if subclinical symptoms of ADHD are considered. In terms of clinical course, ADHD predates the emergence of tics in the majority of cases. The general consensus from various studies comparing control participants to people with TS-only, ADHD-only, and TS+ADHD is that the observed difficulties in relation to behavioural problems, poor social functioning and functional impairment may be attributed to comorbid ADHD rather than tics or tic severity per se (Carter et al., Reference Carter, O'Donnell, Schultz, Scahill, Leckman and Pauls2000; Hoekstra et al., Reference Hoekstra, Steenhuis, Troost, Korf, Kallenberg and Minderaa2004; Stephens & Sandor, Reference Stephens and Sandor1999; Sukhodolsky et al., Reference Sukhodolsky, Scahill, Zhang, Peterson, King, Lombroso and Leckman2003). A diagnosis of ADHD has been shown to be associated with poorer cognitive functioning, and maladaptive and disruptive behaviour. Moreover, children with TS+ADHD have greater difficulties with aggression than those with ADHD-only (Rizzo et al., Reference Rizzo, Curatolo, Gulisano, Virzì, Arpino and Robertson2007).

Thus, it seems that the frequently co-occurring ADHD contributes substantially to psychological and learning problems in children with tic disorders. The impact of ADHD upon learning is well documented and includes resultant difficulties in (a) applying learning; (b) executive functioning difficulties (including problems with managing time, forming goals, organising materials and activities, starting/completing tasks, breaking down long assignments and projects, and storing memories); and (c) attention and impulsivity mediated difficulties with problem-solving and sequencing (Dornbush & Pruitt, Reference Dornbush and Pruitt1995).

Obsessive–compulsive behaviour (OCB) and obsessive–compulsive disorder (OCD) occur in approximately 30–50% of people with TS, with obsessive–compulsive symptoms typically presenting after the tic symptoms (Bloch & Leckman, Reference Bloch and Leckman2009). Like ADHD, the presence of OCD in addition to TS places a young person at considerable risk for a range of psychological and psychosocial morbidities in childhood and adulthood that can be particularly disruptive to learning. Anxious children may find learning difficult, and those with OCD in particular can feel too cognitively ‘stuck’ to learn (Packer & Pruitt, Reference Packer and Pruitt2010). The doubting and checking behaviours that may be present can slow down completion of activities and can be a significant challenge in timed tasks and examinations. Similarly, OCD symptoms can disrupt memory processes, application of strategies, sequencing abilities, and problem-solving. Although these skills do not appear to be deficient per se in children with OCD, they can be disrupted by the cognitive and attentional resources devoted to OCD cognitions and behaviours (Dornbush & Pruitt, Reference Dornbush and Pruitt1995).

Behavioural/emotional problems such as aggression and anger control problems, sleep disturbances, and self-injurious behaviour have been noted to occur at higher than expected levels in people with tic disorders, usually when ADHD or OCD are already present (Freeman et al., Reference Freeman, Fast, Burd, Kerbeshian, Robertson and Sandor2000). Other behavioural/emotional disabilities such as non-OCD anxiety, separation anxiety in particular, and depression/depressive symptoms have also been noted to occur at high levels in individuals with tic disorders (Coffey et al., Reference Coffey, Biederman, Geller, Spencer, Kim, Bellordre and Magovcevic2000). One study observed that 13% of individuals with TS in a sample of 3500 had depression, while 76% of the sample experienced depressive symptoms (Robertson, Reference Robertson2006). It is conceivable that the emergence of depression and anxiety in individuals with existing comorbidities reflects the cumulative psychosocial burden faced by this population (Swain et al., Reference Swain, Scahill, Lombroso, King and Leckman2007).

Also increasingly observed in recent years are the similarities that exist between TS and autism spectrum disorders (ASD). ASD and TS are both neurobiological conditions that predominantly develop during childhood and affect mostly boys, and which consist of stereotypic or repetitive behaviours, ordering or arranging behaviours, as well as echolalia and echopraxia. As is the case in ASD, difficulties with empathy can also occur regularly in people with tic disorders (Kadesjö & Gillberg, Reference Kadesjö and Gillberg2000). Specifically, in that study around two-thirds of 58 children and adolescents with TS, who did not have a comorbid ASD, scored above the clinical cut-off on the Autism Spectrum Screening Questionnaire, and were also rated by their teachers as having major social interaction difficulties. Around one third were also rated as having empathy difficulties (i.e., they were reported to lack the ability to adjust to expectations or demands made by peers and/or they did not notice implicit negative reactions on the part of peers). Abnormal motor movements are present in both ASD and TS; however, the types of movements vary, with tics being experienced in tic disorders and stereotypic movements in ASD. Tics and stereotypic movements can be difficult to differentiate; however, they do have some distinguishing features. Tics tend to be quick movements that last for only brief periods; in contrast, stereotypies are more coordinated and unhurried. Also, tics vary in severity and site over time, whereas stereotypies often tend to remain unchanged. Tics have been shown to occur frequently in people with ASD. Although there is significant variability in the extant research, the literature suggests that around 20–40% of individuals with ASD experience tics (Baron-Cohen, Scahill, Izaguirre, Hornsey, & Robertson, Reference Baron-Cohen, Scahill, Izaguirre, Hornsey and Robertson1999; Canitano & Vivanti, Reference Canitano and Vivanti2007; Ehlers & Gillberg, Reference Ehlers and Gillberg1993). Perhaps the largest and best controlled study to date reported that the occurrence of TS in ASD was 6.5% (Baron-Cohen et al., Reference Baron-Cohen, Scahill, Izaguirre, Hornsey and Robertson1999).

Tics have also been observed in individuals with intellectual disability, with the prevalence of tics appearing to increase with the severity of the disability (Bodfish, Symons, Parker, & Lewis, Reference Bodfish, Symons, Parker and Lewis2000). When individuals with intellectual disability only are studied, the prevalence of tics is reported to be around 5–10% (Bodfish et al., Reference Bodfish, Symons, Parker and Lewis2000; Bradley, Summers, Wood, & Bryson, Reference Bradley, Summers, Wood and Bryson2004). However, consistent with the literature on ASD and tics reviewed previously, when individuals with intellectual disability and ASD are considered over 50% may present with tics.

Why do Tic Disorders and Associated Comorbidities Affect Learning?

The relationship between tics disorders and learning disabilities (taken to mean difficulties with learning rather than intellectual disability) has been studied by examining the prevalence of learning disabilities in cohorts of children with tic disorders, and also the prevalence of tics and tic disorders in cohorts of children attending special education classes.

In terms of cohorts of individuals with tic disorders, learning problems have been identified in around 30–40% of cases (Abwender et al., Reference Abwender, Como, Kurlan, Parry, Fett, Cui and Deeley1996; Burd, Kauffman, & Kerbeshian, Reference Burd, Kauffman and Kerbeshian1992; Erenberg, Cruse, & Rothner, Reference Erenberg, Cruse and Rothner1986). A more recent study suggested that in uncomplicated TS (i.e., TS without any comorbidities) only 11% of children had academic difficulties, whereas when TS was comorbid with ADHD, this figure rose to 31%. The full range of specific learning disabilities was observed in children with tic disorders, although difficulties with reading and handwriting tended to predominate (Packer, Reference Packer2005).

In special education/learning disability classes, several studies have indicated a prevalence of around 20–45% for tic disorders (Comings & Comings, Reference Comings and Comings1987; Eapen et al., Reference Eapen, Robertson, Zeitlin and Kurlan1997; Khalifa & von Knorring, Reference Khalifa and von Knorring2003; Kurlan et al., Reference Kurlan, Como, Miller, Palumbo, Deeley, Andresen and McDermott2002; Kurlan et al., Reference Kurlan, McDermott, Deeley, Como, Brower, Eapen and Miller2001; Kurlan, Whitmore, Irvine, McDermott, & Como, Reference Kurlan, Whitmore, Irvine, McDermott and Como1994) and around 7–20% for TS (Eapen et al., Reference Eapen, Robertson, Zeitlin and Kurlan1997; Kurlan et al., Reference Kurlan, McDermott, Deeley, Como, Brower, Eapen and Miller2001). Given that the prevalence of TS is thought to be around 1% in the community, the observed rate in these settings is thus approximately 10 times higher.

Burd, Freeman, Klug, and Kerbeshian (Reference Burd, Freeman, Klug and Kerbeshian2005) reported that around 23% of people with tic disorders have learning disabilities. These authors identified phenotype differences between the tic disorder−LD group and the tic disorder+LD group, with the tic disorder+LD group more likely be male and have (a) an age of tic onset before 8 years and presentation for evaluation before 18 years, (b) fewer family members affected by tics, (c) a history of perinatal problems, and (d) more comorbidities. These features tend to suggest the role of additional nongenetic factors, or ‘second hits,’ such as perinatal events, trauma, injury, hypoxia, neural and psychosocial stressors that affect neuronal development with consequent impairment in cognitive processes and learning (Eapen, Reference Eapen2011).

Although comorbid ADHD can lead to educational difficulties and underachievement in its own right, the presence of learning disability should always be a consideration when working with children who have tic disorders, even where ADHD is not present (Eapen & Črnčec, Reference Eapen and Črnčec2009). This is because learning and cognitive performance can be affected in tic disorders in a number of ways. These include (a) deficits that are integral to tic disorders; (b) deficits arising from efforts at tic suppression; (c) deficits resulting from compensatory mechanisms (neural and otherwise); (d) factors that affect neuropsychological test performance, such as fluctuations in cognitive performance due to waxing and waning course; (e) effect of medication, such as sedation and cognitive slowing; and (f) the impact of comorbidities. All of the above factors may independently and collectively contribute to neuropsychological and executive function impairments noted in tic disorders and may explain the variation in performance across studies.

Studies in individuals with tic disorders have reported increased intrusions during recall on a word list suggesting an inhibitory dysfunction during learning tasks (Mahone, Koth, Cutting, Singer, & Denckla, Reference Mahone, Koth, Cutting, Singer and Denckla2001). This inhibitory dysfunction may be at the core of the attentional impairment found in uncomplicated TS. In this regard, Johannes et al. (Reference Johannes, Wieringa, Nager, Müller-Vahl, Dengler and Münte2001), using event-related brain potentials, observed that although children and adults with TS showed normal behavioural performance on a dual-performance task, they demonstrated evidence of increased attention to irrelevant stimuli. Thus, the person with a tic disorder may have difficulty in keeping at bay the interference from irrelevant stimuli. This is in keeping with the observation that people with tic disorders constantly experience somatosensory urges and premonitory sensations that represent a loss in the normal ‘automatic’ ability to suppress or ‘gate’ irrelevant information in sensory, motor, and cognitive domains. These experiences, described as the ‘relentless drumbeat’ (Leckman, Bloch, Scahill, & King, Reference Leckman, Bloch, Scahill and King2006), intrude into conscious awareness resulting in the generation of tics and related symptoms.

Strategies to Assist Students With Tics in Special Education

Although there is certainly no requirement upon educators to become ‘experts’ in tic disorders, a degree of familiarity with tic disorders would seem to be critical given the high rates of students affected in special education contexts. The seemingly purposeful nature of tics can lead to a management approach based on behavioural contingencies. For example, the young person may be punished for the ‘misbehaviour’ of ticcing or otherwise advised to ‘stop it’, or rewarded for not engaging in tics. Unfortunately, the mismatch between the young person's lived experience of tics as involuntary and a punishment/rewards management approach often leads to stress and tic exacerbation. Similarly, the waxing and waning course of tics can often lead to a sense that an individual may be ‘doing it on purpose’ during a waxing phase. A school-wide culture of familiarity with the involuntary nature of tics and tolerance of tics within the school can also lead to reductions in, and more appropriate management of, any bullying by peers. Suitable accommodations for children with tic disorders require something of a balancing act between including the student in all school activities and organising their experience so that they can participate on their own terms. In general terms, the aim is to create an environment that is emotionally ‘safe’ and where tics are proactively managed.

Management strategies need to be tailored to the individual child. For example, for some children, stress and unpredictable events will exacerbate tics, whereas for others boredom may serve to exacerbate their tics. In addition to management strategies suited to children with learning and disruptive behavioural difficulties, some general management strategies are detailed in Table 2.

TABLE 2 School-Based Strategies to Assist Young People With Tic Disorders

With children, active collaboration and feedback between family and school is essential to facilitate appropriate classroom management and optimal curriculum planning; for example, in identifying times of day when tics may be worse, fostering the young person's strengths and interests, and revising strategies in use in response to any issues that have arisen. For adolescents and adults, appropriate adaptations may be needed at home or in the workplace.

We will not review here strategies for management of comorbidities such as ADHD and OCD within the classroom, as these have been published elsewhere (e.g., Packer & Pruitt, Reference Packer and Pruitt2010). Nonetheless, management of comorbidities is often equally, if not more, critical than management of tics themselves. Further, familiarity with some of the features of and complexities surrounding tic disorders will assist in the task of differentiating between oppositional and disruptive behaviours, and tics.

Overview of Medical Management

Pharmacological treatment for tic disorders may include clonidine, especially when ADHD presents comorbidly, or antipsychotic agents such as risperidone when there are comorbid behavioural problems such as irritability, aggression and insomnia or ASD (Eapen & Gururaj, Reference Eapen and Gururaj2005; Eapen & Sachdev, Reference Eapen and Sachdev2008). Comorbid conditions such as OCD and ADHD would need attention and may necessitate treatment with specific serotonin reuptake inhibitors, and stimulants (with caution, monitoring for tic exacerbation) or atomoxetine, respectively. The risk of drug interactions and side effects may be increased in those with brain damage or epilepsy, and gradual increase in dosage with close monitoring is recommended (Eapen & Črnčec, Reference Eapen and Črnčec2009; Eapen & Sachdev, Reference Eapen and Sachdev2008). Psychotherapeutic techniques such as cognitive–behaviour therapy for OCD or comprehensive behavioural intervention for tics (CBIT) have established efficacy (Piacentini et al., Reference Piacentini, Woods, Scahill, Wilhelm, Peterson, Chang and Walkup2010; Watson & Rees, Reference Watson and Rees2008); however, outcomes may be constrained in individuals where poor cognitive and learning abilities, and hyperactivity, are a factor. Other strategies for minimising tics include input around engendering calm and consistent family dynamics and routines, the use of physical activity to ‘channel’ energies, as well as encouraging the individual with tics to engage in talents and hobbies, as hyperfocused activity often reduces tic expression.