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Tics and Problem Behaviors in Schoolchildren:
Prevalence; Characterization, and Associations

Snider LA, Seligman LD, Ketchen BR, et al (NIH, Bethesda , Md ) Pediatrics 110:331-336, 2002 4-10

Background — Between 5% and 20% of schoolchildren experience a simple or complex motor or vocal tic at some time in their lives. Reports indicate that children are 5 to 12 times more likely to be diagnosed with a tic disorder than adults and that boys are diagnosed at a higher rate than girls. Tics tend to be transient, meaning that they may be debilitating for a period, then relatively quiescent for an even longer time. To assess the severity of a tic, one must take into account its frequency, intensity, and complexity. The prevalence of tics and problem behaviors was assessed using monthly systematic observations during a period of 8 months.

Methods — The study included 553 children in kindergarten through sixth grade who were observed and evaluated by 3 raters from November 1999 to June 2000. For motor tics, location and severity were documented, using a scale ranging from 0 (none) to 3 (severe). For problem behaviors, ratings included 0 (absent), 1 (subclinical), and 2 (clinical) in the following 6 categories: disruptive, hyperactive, impulsive, aggressive, anxious, and distracted.

Results — During at least 1 month of observation, motor tics were observed in 135 (24.4%) of the children, and the monthly prevalence was 3.2% to 9.6%; it was significantly higher in November through February than in March through June. The boy-to-girl ratio for motor tics was 2:1. In sixth grade, the rate of motor tics was 15%, while in first grade it was 47%. 68% percent of the motor tics affected the eye; 47%, the mouth; 25%, the nose; 8%, the head, neck, or both; 2%, an extremity; 1%, the trunk; and 10%, other areas. Any observed problem behavior was not present to a greater extent in children with motor tics than in those without tics, nor were children with a problem behavior more likely to have tics. Eighteen percent of the children with motor tics had an isolated variety, meaning the tics were present for only 1 or 2 consecutive months; 6.1 % had persistent motor tics, meaning they were noted for 2 nonconsecutive months or during more than 3 months. Persistent motor tics tended to be significantly more severe and to occur in boys rather than girls at a rate of 7.5:1. Those with persistent tics were also more likely to have problem behaviors than were those with isolated tics (41% vs 23%).

Conclusions — Motor tics and problem behaviors were seen in about one fourth of the elementary schoolchildren observed. These disorders did not appear to be linked, and, in most instances, were transient and lasted only for 1 month of the study.

Dr Jeffrey E. Lazarus, Associate Clinical Professor, Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio , comments:

It used to be believed that tics are involuntary; however, many children can control their tics, particularly, if they're concentrating intently on something, or, if they're enjoying themselves. To have an observer at the front of the room, or moving about the room, might be quite distracting and might affect a child's tics and/or behavior. It might motivate some children to control their tics even more, and, perhaps, in other children, the presence of the observer might be a stressor that, in fact, triggers tics to increase. The same may also be true for problem behaviors.

It's been repeatedly described that some children may have many more tics at home than at school; that is, they may "let it all hang out" at home, perhaps because they know intuitively that they and their tics are more accepted at home than at school. In school, children may work harder, mentally, to control tics to avoid unpleasant comments, imitation, and ridicule.

Many children have an increase in their tics, particularly, children with Tourette's syndrome, at the beginning of the school year. This is commonly believed to be due to increased stress in school. Therefore, by excluding September and October in this study, we may be missing some increase in tic behavior.

The suggestion of a relationship between tics and streptococcal infections is an intriguing one. I wonder how often general pediatricians treat streptococcal infections in patients who subsequently develop tics. Remember that the onset of pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) can be extremely variable. Sometimes symptoms appear quite quickly after streptococcal infections, and exacerbations may not present until long after the infection has passed."'

In this particular protocol, a 3-minute observation time per child might be too short. According to videotape studies of patients with Tourette's syndrome, a minimum of 5 minutes will give a better estimate of tic frequencies. (3)

It would have been interesting to see how the children in this study perceived themselves and each other regarding the parameters being judged. In addition, it would have been interesting to see how the children thought that OTHERS perceived THEM.

The study shows that motor tics are common in this age group, yet most are mild and resolve quickly. Therefore, it's probably safe to delay referral of these children to a specialist.

By its very nature, biobehavioral research is difficult, with the typical criticism being lack of objectivity. The authors are to be complimented on this first attempt to define frequencies and associations of tics and problem behaviors. Future studies that include children's perceptions of themselves and others, and then compare that information to the perceptions of teachers, parents, and other adult caretakers may help in understanding not only the frequency, location, timing, and relationship of tics and problem behaviors (both at home and at school) but also the impact they have on their lives. Lastly, to paraphrase what we were taught in medical school, "When you hear hoof beats, think of horses first, then PANDAS, and then zebras!"

References

1. Garvey MA: personal communication.
2. Garvey MA, Deidd J, Swedo SE: PANDAS: The search for environmental triggers of pediatric neuropsychiatric disorders. Lessons from rheumatic fever. J ChildNeurology 13:413-423, 1998.
3. Chappell PB, McSwiggan-Hardin MT , Scahill L, et al: Videotape tic counts in the assessment of Tourette's syndrome: Stability, reliability, and validity. J Am Acad Child Adolesc Psychiatry 33:386-393, 1994.