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Wednesday, 8 September, 1999, 18:19 GMT 19:19 UK
Taking control of Tourette's
The decision-making part of the brain could be the cause
Sufferers of Tourette's syndrome may have more control over their swearing and twitching than anyone has realised.

Psychologists in Canada said the condition - in which patients suffer muscular spasms and outbursts of obscenities - is caused by a psychological rather than physical disorder.

Doctors had thought that these spasms were totally involuntary but the new research suggests they are intentional, co-ordinated movements made in response to some irresistible urge.

The theory is that while most people will often feel the urge to do or say something inappropriate but decide not to go ahead, in people with Tourette's, this mechanism may have broken down

Muscle action

Dr Randy Flanagan and a team at Queen's University in Kingston, Ontario, studied BF, a young man with Tourette's syndrome.

Using sensors attached to a weighted box, they looked at how BF's grip changed when he moved his arm.

If the tics suffered as part of the syndrome were uncontrollable spasms, BF would not have time to adjust his grip when a tic occurred.

However, BF was able to anticipate each tic and adjust his grip on the box accordingly - suggesting he was at some level in control of his actions.

This level of control was mirrored in four participants who did not have the syndrome but went through the same test.

Unanswered questions

"What the finding strongly suggests is that the disorder, at least in the individual we examined, is a high-level disorder rather than a low-level motor disorder," Dr Flanagan told BBC News Online.

This means defects in the parts of the brain responsible for planning and decision making could be behind the condition, he said, although the exact level of control was difficult to gauge.

"They have motor control over these tics, and these movements look normal and have all the same sort of response we would expect to see in voluntary movement.

"The question of whether they have control over these movements is a good one and is still open."

However, once resolved, it may pave the way to behavioural therapy for the syndrome.

Inappropriate movement

Another interesting observation the team made in its study involved the method they used to get the subjects to make a tic movement.

They told the subject to make a movement, but only when they were given a certain signal - such as a finger click.

As the subject waited for the signal, they would suffer a tic - it seemed as if they had the urge to make the movement but would check themselves before going too far.

"It is almost as if we set up a plan of action in their heads but they then couldn't suppress it until the appropriate time," Dr Flanagan said.

"We want to further test this idea in various ways - where we set up an action plan and then look at how it's expressed at an inappropriate time."

The team is performing further studies involving more people and more tasks to gain a better understanding of these tics and how they work.

The study was published in the journal Experimental Brain Research and reported in New Scientist magazine.

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