Tics are sudden, repetitive movements and vocalizations that typically are brief but occur in bouts. For example, blinking, nose twitching, and rapid jerking of any part of the body are common motor tics, and throat clearing, coughing, and grunting are simple phonic tics (Leckman et al., 2013). The complexity of tics ranges from brief and meaningless to longer and seemingly purposeful behaviors. Tics can take the form of obscene movements (copropraxia) or expression of obscene words or phrases (coprolalia). Vocal tics can involve repetition of one’s own words (palilalia) or the words of others (echolalia). In addition to varying in severity, tic disorders are often associated with other behavioral problems such as inattention, hyperactivity, anxiety, and irritability. Tic disorders and associated conditions have traditionally been evaluated and treated by neurologists and psychiatrists. More recently, behavior therapy known as habit reversal training (HRT) has been shown to be a helpful treatment for tic disorders, reflecting the somewhat unique way in which these conditions seem to be at the interface of “mind and body.”

Tics have been observed for hundreds of years and were once viewed as examples of demonic possession. The modern study of tics began in France with the work of Itard and Gilles de la Tourette in the second half of the 19th century. Regarding diagnostic criteria and features, in 1885 Gilles de la Tourette described nine patients with motor and phonic tics and noted that tics were characterized by childhood onset, lifelong duration, and a waxing and waning course. These characteristics have since been confirmed in a large number of clinical series worldwide (Lin et al., 2002; Robertson et al., 1988). Of note, coprolalia, a feature that has become engraved in the public view of Tourette’s syndrome (TS) (Olson, 2004), is present only in 15% to 20% of cases in clinical samples (Freeman et al., 2009). Several types of tic disorder are presently recognized. The distinctions among these types have to do with the persistence of tics (chronic or transient) and whether vocal as well as motor tics are observed (both are seen in Tourette’s disorder). A diagnosis of tic disorder is not made if the tics are caused by another medical condition (e.g., Huntington’s disease or postviral encephalopathies) or physiologic effects of a substance (e.g., cocaine).

In chronic or persistent vocal or motor tic disorder, the tics (either vocal or motor but not both) have lasted for at least 1 year without a long symptom-free period. The tics wax and wane over time and can be simple or more complex with a broad range of severity. Motor tics are more common than vocal tics and usually involve the head and upper body. As with other tic disorders, the tics can be voluntarily suppressed for periods of time and are exacerbated by stress. The condition may persist into adulthood and become noticeable at times when the individual is fatigued or anxious (Box 16.1).

If both motor and vocal tics are present, a diagnosis of Tourette’s disorder is made. Tourette’s disorder is the best known of the tic disorders. In Tourette’s disorder, both vocal and motor tics must be present. Tourette’s disorder usually has its onset in childhood with simple motor tics, often involving the head or face (e.g., eye blinking or head jerks). Gradually, tics come to involve other regions of the body, often following a “rostral to caudal” progression (i.e., head to rest of body). As motor tics persist, they may have a negative impact on the child’s functioning. Typically, vocal or phonic tics usually begin after the motor tics but then have a progression from more simple manifestations (throat clearing) to much more complex forms such as echolalia and coprolalia in a minority of cases. The severity of symptoms tends to a peak in middle childhood (Figure 16.1). As noted subsequently, various other disorders may coexist with Tourette’s disorder and may, in some ways, pose even greater obstacles for treatment (Boxes 16.2 and 16.3).

Transient tics are frequent in childhood but often are of brief duration. On the other hand, sometimes the onset of motor tics marks the onset of Tourette’s disorder often between ages 5 and 7 years. In this condition, motor tics persist and generally progress down and away from the midline (e.g., head, neck, arms, and, last and least frequently, the lower extremities). Phonic tics usually appear after motor tics and are rare in isolation. Tic complexity changes with age, although most individuals with Tourette’s disorder have a diagnosis in childhood. It is important to note that the severity of tics in Tourette’s disorder waxes and wanes over time. Tics can be voluntarily suppressed for brief periods and are exacerbated by stress, fatigue, and lack of sleep. Tic episodes occur in bouts, which also often cluster. The pattern of tics is highly unique to the person. Often, as children with Tourette’s disorder become older, they develop a sense that a tic is about to happen and may be able to exert some control over them, although this also serves as a source of anxiety and worry and can require much effort.

In some cases, tics are frequent and forceful, resulting in social impairment or, rarely, physical disability. However, in some individuals, tics may be frequent but may go unnoticed
and do not interfere with daily living (Coffey et al., 2004). Overall impairment, however, may not be directly related to tic severity. Some patients with TS and mild tics may be distressed and impaired, whereas some patients are seemingly unaffected by their more prominent tics. Consequently, the tic-related impairment is not part of the current diagnostic criteria for TS. However, individuals who meet some but not all criteria for TS or chronic tic disorder but present with clinically significant distress or impairment can be diagnosed with unspecified tic disorder (American Psychiatric Association, 2013).

Although TS is defined by motor and phonic tics, individuals with TS also experience premonitory urges, recurrent unpleasant sensations associated with the tics. The urges are commonly described as discomfort, pressure, or tingling localized in the muscles involved in the performance of the tics. These premonitory sensations prompt the performance of the tic, which is followed by momentary relief of the associated discomfort. Up to 90% of individuals with TS report the experience of premonitory urges (Banaschewski et al., 2003), and some describe the urges as more bothersome than the tics themselves. Tics involving head, neck, and shoulder movements are associated with particularly prominent urges (Leckman et al., 1993). It has been argued that tics may represent a voluntary response aimed at reducing the discomfort associated with premonitory urges (Lang, 1991). As with tics, the occurrences of urges vary in their frequency, intensity, and duration. The intensity of the urge can vary from fleeting and easily ignored to irresistible and inevitably leading to a tic. Despite the growing consensus that the premonitory urges trigger performance of the tics, the mechanisms of premonitory urges remain poorly understood (Leckman et al., 2006). A closely related phenomenologic aspect of TS is the often-reported capacity to suppress tics, at least temporarily. Even though tics are involuntary, they can be suppressed for minutes or even hours, which may result in uncertainty regarding the voluntary control of tics. Many patients report that the intensity of premonitory urges increases during tic suppression.

Transient tic behaviors may be seen in 2% to 10% of school-age children. The prevalence of chronic motor tics is about 1%. Estimates of the frequency of Tourette’s disorder (vocal and motor tics) vary considerably depending on the age group studied and definitions used; it appears that among older adolescents and adults, the rate is on the order of 4.5 per 10,000. This number is higher for younger children, many of whom improve over time or are not impaired by the condition. The best current estimate of the prevalence of TS was reported to be 14 per 1000 children (Scahill et al., 2013). Tic disorders are 3 to 4 times more common in boys than in girls (Centers for Disease Control and Prevention, 2009).

Tics may be only one part of a constellation of problems that children with Tourette’s disorder may experience. Indeed, 50% or more of referred children with Tourette’s disorder are diagnosed with comorbid ADHD in clinical samples, although epidemiologic studies show a much lower rate (Figure 16.2). At least more than 40% of individuals with Tourette’s disorder experience recurrent symptoms of OCD. Tourette’s disorder is also associated with higher rates of mood and anxiety disorders (Coffey et al., 2000; Robertson et al., 2002), disruptive behavior (Sukhodolsky et al., 2003), and learning disabilities (Yeates & Bornstein, 1996).