Involuntary Movements Called Tics

NEW YORK (Reuters Health) - Children with attention-deficit/hyperactivity disorder (ADHD) sometimes develop involuntary movements called tics. For many years, researchers and parents have questioned whether ADHD medications such as Ritalin might be the cause.

But a growing body of research demonstrates that tics can arise in kids with ADHD whether or not they take medication. For example, a recent study found that 5% of non-medicated kids with ADHD also have tic disorders, and were 60 times more likely than their peers without the attention disorder to have Tourette's syndrome.

ADHD--characterized by developmentally inappropriate impulsivity, inattention and hyperactivity--affects 3% to 5% of school-age children. In Tourette's syndrome, which usually appears in childhood and eases over time, a patient has repeated tics, often associated with noises and cursing.

"What we are discovering now is tic disorder is closely related to attention-deficit/hyperactivity disorder without medication," lead author Dr. Atilla Turgay of the University of Toronto in Canada told Reuters Health.

Turgay and his team measured the prevalence of tic disorders in 880 children and teens with ADHD who had never been treated with stimulants such as Ritalin. The researchers presented their findings last week at the Canadian Pediatric Society's annual meeting in Toronto.

The investigators found that slightly more than 5% of the ADHD patients also had tic disorders, which could include single movements, multiple movements or verbal tics such as in Tourette's syndrome.

So why do the two conditions appear to be linked? "There must be some biological, genetic and neurological type of interrelationship," Turgay said, which needs to be teased out further in studies of the brains of ADHD patients, and also through investigations into genetics, he added.

Turgay and his team also found that tic disorders were more common in boys than in girls. Kids with ADHD and tic disorders were also more likely than others to have obsessive compulsive disorder and generalized anxiety disorder, but were less likely to exhibit conduct disorders.

In an interview with Reuters Health, Dr. Roger Kurlan of the University of Rochester in New York, who reviewed the findings from Turgay and his team, agreed that medications are not likely to blame when children with ADHD develop tics. Rather, he explained, kids often develop tics within a year or two after they have been diagnosed with ADHD, whether or not they take stimulant medications such as Ritalin.

"Study after study after study is showing that medication is not part of the (tic) disorders," he said. "It's just part of the natural course of ADHD."

In fact, Turgay and his team may have actually underestimated the rate of tics in children with ADHD, Kurlan said, for previous studies have identified the disorders in a much higher percentage of ADHD patients.

By Alison McCook
Last Updated: 2002-06-25 13:01:00 -0400 (Reuters Health)