Occasional tics found in one quarter of school children are not linked with behavioural problems
Issue No:
Child Health Monitor, Volume 3, Issue 6
August 2002
Background:
Tics are repeated involuntary muscular movements, affecting either limb muscles, facial muscles (e.g. grimacing or eyelid flicking) or vocal muscles (grunting or saying words). While the classic multiple tic disorder, Tourette syndrome, is not common, some suggest that between five and 20% of all schoolchildren will have a simple or complex tic at some time during childhood (although most disappear). This wide variation in estimates of the frequency of tics, probably reflects variations in research methods, including different methods of assessing tics, the transient nature of many tic problems in children, plus the fact that many studies are done just on children who present to health professionals rather than on whole population samples (the most accurate).
While a lot is known about the behavioural issues linked to Tourette syndrome (e.g. obsessive compulsive disorder and ADHD are common, as well as many other behavioural problems), little is known about the behavioural problems linked to milder forms of tic disorders or the transient tics seen in many otherwise healthy children. Those who treat tic disorders find that children with tics often have accompanying behavioural difficulties, including disinhibited speech or conduct, impulsivity, distractibility, hyperactivity, and occasionally, obsessive-compulsive symptoms. In many cases, for example where the tics are very minor such as eyelid tics, the behaviour symptoms are much more of a problem than the actual tics.
To date, no researchers have looked at the relationship of tic symptoms and problem behaviours in schoolchildren over a period of time sufficient to take account of variations in tic disorders and transient tics. This is important, as finding a link between common tics and conduct may help to explain the reasons why many children have problem behaviours, revealing the organic or neurodevelopmental basis of some of these behaviours.
Findings:
These US researchers studied 553 children from Washington DC in classes from kindergarten through to sixth grade in one large elementary school. They studied all the children monthly for seven months, studying how often they had tics and whether they had behavioural problems. The rating of the tics and behaviours was done as objectively as possible by one of three trained raters who spent time in each class (three minutes observing each child) each month over the period. They rated motor (movement) tics by location and severity from absent to severe. They did not try to record vocal tics due to the background classroom noise. Behaviour problems were rated from absent, subclinical (meaning mild) and clinical (meaning significant problem) in six categories: disruptive, hyperactive, impulsive, aggressive, anxious, and distracted.
They found that, over the whole period of the study, around one-quarter of all children (24.4%) were found to have a motor tic. Month by month, the prevalence (rate) of tics ranged from a low of 3% during the summer months to a high of 9.6% of the children during the winter months. Overall, boys were twice as likely to have tics as girls. Almost seventy percent (68%) of all the tics noted were eye tics, with mouth, nose and neck tics next in descending order. Overall, children with tics were no more likely to have problem behaviours than children who did not have tics.
Around 6% (6.1%) of the group had persistent or multiple tics, and these children were almost twice as likely as those with transient tics, to have behaviour problems. Problem behaviours were also significantly more common during the winter months when tics were more common.
They concluded that while almost a quarter of all children had some tics, the great majority were transient and not linked with problem behaviours. About 6% of children have a more serious tic disorder, lasting for longer and linked with problem behaviours.
Comments:
This evidence strongly suggests that occasional tics are quite normal in healthy children – and that around one-quarter of all children will have them in a six month period. These minor transient tics do not persist and are not linked with behaviour problems, which is clear evidence that they do not reflect an underlying neurological disorder.
Persistent, multiple or complex tics were found in about one in 20 children, and these were linked with behavioural problems. It is possible that the tics caused the behavioural problems, but it is more likely that both the tics and behaviours reflect an underlying neurodevelopmental problem.
This was an observational study, so the findings are limited by how carefully and objectively the researchers noted down their findings on each child. They seem to have been very objective. However, their methodology meant that they could not observe the frequency of vocal tics (certainly a major omission), and they only observed each child for three minutes each month which is surely not sufficient to definitely document the presence or absence of a tic or behaviour.
The researchers claim that their methods are more accurate than using parents to report tics or behaviours, as previous studies have done. This is clearly debatable.
Reference:
Snider et al. Tics and Problem Behaviors in Schoolchildren: Prevalence, Characterization, and Associations. Pediatrics August 2002; 110: 331-336.
Action Points:
- Almost one-quarter of elementary school children will have at least one tic over a six-month period. These tics are normal and are not linked with behavioural problems. Parents should not be concerned about occasional minor motor or vocal tics in their children.
- Boys are twice as likely as girls to have tics, and tics are more common in winter.
- About one in 20 children have a significant tic issue, often with accompanying behaviour problems.
Reproduced with permission of ChildHealthMonitor.org, which translates pediatric journal articles into everyday language providing comprehensive information on research breakthroughs ranging from general nutrition to rare diseases. A great resource for busy Pediatricians and also for parents who want to learn how best to care for their children's medical and parenting problems.
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