Tourette syndrome affects a far larger area of the brain than previously thought, a new study at BSMS shows. Brain scanning has revealed that a much wider network of brain areas can be affected than just the areas responsible for movement.
Tourette’s is a neurodevelopmental condition characterised by chronic multiple tics, physical or verbal, which feel compulsive and ‘unwilled’. These rapid recurrent actions or vocalisations can range from simple brief acts such as blinking or coughing to complex action sequences. Patients can differ markedly in the frequency, severity and bodily distribution of their tics. Moreover, they will frequently also have other conditions such as attention deficit hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), anxiety disorders or depression.
Researchers at BSMS conducted a ‘meta-analysis’, pooling together the results from a number of individual studies that looked at changes in the brain identified through functional MRI (fMRI) scanning among people with tics.
“We predicted that we would see evidence across the fMRI studies for changes in activity in movement regions of the brain in Tourette syndrome,” says Dr Charlotte Rae, Research Fellow at BSMS. “But we were surprised to see that not only was there evidence for altered activity in the areas responsible for movement, there was additional evidence for much more widespread alterations across many regions of the brain, including prefrontal cortex, somatosensory cortex (which registers bodily sensations), and even visual areas.
“We believe that this may represent the diversity of individuals who have Tourette syndrome, with widely varying symptom profiles, not just in tics, but also in accompanying conditions, such as ADHD and OCD.”
However, when it came to altered activity in regions that were specifically linked to the severity of a patient’s tics, only the movement planning areas of the brain were identified. This suggests there are indeed quite specific changes in movement circuits of the brain that relate closely to tics, while other features of the condition may be driven by alterations in brain regions outside the core movement areas.“
As the wider variation of anatomical alterations may be linked to participants’ other conditions, the medication they might be on, or their stage of neurodevelopment, we believe that further studies need to address these differences. These would help us develop a more precise understanding of patients’ brain activity and work on further treatments for this condition,” says Dr Rae.