PEOPLE who swear and twitch because they have Tourette鈥檚 syndrome are more in
control of their actions than anyone realised. A psychologist in Canada has
found the first direct evidence that their tics are intentional, coordinated
movements made in response to some irresistible urge, rather than involuntary
spasms.
The symptoms of Tourette鈥檚 range from excessive twitching to extreme bouts of
inappropriate swearing. Doctors have assumed that the tics and verbal outbursts
are involuntary, says Randy Flanagan of Queen鈥檚 University in Kingston,
Ontario.
To test this, Flanagan and his colleagues studied the movements of a young
man with Tourette鈥檚, 鈥淏F鈥�, by asking him to hold a small weighted box fitted
with sensors that recorded his grip force and movements. The sensors measured
how BF modified his grip on the box when asked to move his arm.
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If the tics were spasmodic reflex actions, BF would not have time to adjust
his grip during a tic. But the researchers found that he anticipated each tic
and increased his grip, just as he and four subjects who did not have Tourette鈥檚
did during voluntary movements (Experimental Brain Research, vol 128, p
69).
Flanagan believes this is evidence that Tourette鈥檚 is not a simple motor
disorder but a higher-level problem. He thinks it is like obsessive compulsive
disorders, which affect the circuits of the brain鈥檚 premotor frontal lobe and
basal ganglia鈥攁reas that control planning and decision making.
Most people have the urge to say or do inappropriate things, but decide not
to, says Flanagan. But Tourette鈥檚 sufferers lack the ability to suppress these
impulses. 鈥淚t鈥檚 probably an extreme variant of a normal thing felt by many
people,鈥� he says.
鈥淚t鈥檚 a nice observation,鈥� says John Rothwell, an expert on movement
disorders at the Institute of Neurology in London. 鈥淚t may tell us something
about how the brain makes normal voluntary movements,鈥� he adds.