Researchers have discovered the mechanism in the brain responsible for the motor and vocal tics found in Tourette Syndrome. The study, published in the British Psychological Society’s Journal of Neuropsychology, could at some point lead to new non-drug therapies.
“This new study is very important as it indicates that motor and vocal tics in children may be controlled by brain changes that alter the excitability of brain cells ahead of voluntary movements,” said cognitive neuroscientists Stephen Jackson, Ph.D., of the University of Nottingham.
“You can think of this as a bit like turning the volume down on an over-loud motor system. This is important as it suggests a mechanism that might lead to an effective non-pharmacological therapy for Tourette Syndrome.”
Tourette Syndrome affects around one child in every 100 and usually begins in early childhood. During adolescence, there is a period of “pruning back” in which redundant brain connections are removed and other structural and functional brain changes occur.
During this time, around one-third of children with Tourette Syndrome will find that their tics disappear and another third are able to more effectively control their tics. The remaining third, however, will experience little or no change in their tics and are likely to remain troubled by their Tourette Syndrome symptoms into adulthood.
This phenomenon suggests that there are mechanisms in the brain that are involved in controlling tics and undergo development or re-organization in the teen years.
“The research is based on the general hypothesis that an area in the brain called the striatum is overactive as a result of alterations in the early development of the brain. As a result, the signals that are relayed to the brain’s cortex region lead to hyper-excitability and cause tics to occur,” said Ph.D. student Amelia Draper.
“We have looked at how that hyperactivity and the resultant tics might be controlled by finding a way to ‘turn down the volume’ on that cortical excitability. This is potentially extremely important as the parents of children with tics are desperate to find a safe and effective therapy that is an alternative to drug treatments.”
During the study, the researchers used a method called Transcranial Magnetic Stimulation (TMS) in which a magnetic field is passed over the brain to produce a weak electrical current which stimulates motor function to induce a twitch response.
As participants with Tourette Syndrome were about to undertake a hand movement, the researchers were able to measure alterations in brain excitability just before the movement and chart the differences between each person.
The study showed that subjects with Tourette Syndrome, unlike those of a similar age without the condition, were least able to modulate the hyperactivity in the brain.
“For the one-third of people who aren’t going to get better this could offer them a much needed assistance with controlling their tics, while relying less on other conventional pharmaceutical therapies which can have associated side effects such as weight gain or tiredness,” said Jackson.
Source: University of Nottingham