Neuroimaging scans revealed that patients with persistent Tourette’s syndrome had higher levels of neuronal density and immature functional connectivity patterns, compared with healthy controls.
HONOLULU—Patients with Tourette’s syndrome may have lower tic remission rates than previously described, according to research that was presented at the 63rd Annual Meeting of the American Academy of Neurology. Neuroimaging analysis showed that these patients also have increased neuronal density in certain regions of the brain.
“While up to half of individuals report ‘virtual remission’ of symptoms by young adulthood, tics recognizable by an expert observer are often still present,” the investigators, led by David Shprecher, DO, stated.
Dr. Shprecher, Assistant Professor of Neurology at the University of Utah in Salt Lake City, and colleagues conducted neuroimaging scans of patients with Tourette’s syndrome and controls to gather preliminary data about the rates and neuroimaging features of remission and persistent tics in the study population.
The researchers performed scans on 10 men (age range, 19 to 32) with previous social or academic impairment associated with Tourette’s syndrome and had not used tic-suppressing drugs in the last six months, as well as on 10 neurologically normal control patients. The neuroimaging techniques used included structural/volumetric MRI, diffusion tensor imaging, MR spectroscopy, and resting-state fMRI.
Few Participants Experienced Remission of Symptoms
Using the Yale Global Tic Severity Scale (YGTSS) to determine the degree of symptom regression, the researchers found that patients with Tourette’s syndrome experienced a mean reduction in tic severity of -16.1% (YGTSS total) and -24.6% (motor and vocal). “Only two subjects professed remission,” the researchers wrote, “with drops from mean 45 to 16.5 (YGTSS total) and 30 to 11.5 (YGTSS motor and vocal).”
The investigators focused on the anterior cingulate cortex as a region of interest for neuroimaging analysis. MR spectroscopy showed that patients with Tourette’s syndrome had increased N-acetyl-aspartate to creatine ratios compared with controls, which the researchers noted could be due to the presence of an increased neuronal density in the anterior cingulate cortex. “The [MR spectroscopy] findings suggest that limbic (not just motor) circuits are worthy of further study with this and other neuroimaging techniques,” they wrote.
Dr. Shprecher’s team also reported that resting-state fMRI showed significantly increased connectivity between occipital regions in patients with Tourette’s syndrome. They noted, “The resting-state fMRI data suggest this modality can be useful in studying influence of early cognitive behavioral intervention therapy on maturation of brain circuits and Tourette’s syndrome outcome over time.
“For individuals meeting original DSM-IV Tourette’s syndrome criteria, tic remission may be less common than previously described,” the investigators concluded. “Persistent Tourette’s syndrome may be characterized by increased neuronal density in the anterior cingulate cortex. Immature functional connectivity patterns … are also present in young adults with persistent Tourette’s syndrome symptoms.”
Church JA, Fair DA, Dosenbach NU, et al. Control networks in paediatric Tourette syndrome show immature and anomalous patterns of functional connectivity. Brain. 2009;132(pt 1):225-238.
Coneleaa CA, Woods DW, Brandt BC. The impact of stress induction task on tic frequencies in youth with Tourette syndrome. Behav Res Ther. 2011 May 25; [Epub ahead of print].
Mazzone L, Yu S, Blair C, et al. An FMRI study of frontostriatal circuits during the inhibition of eye blinking in persons with Tourette syndrome. Am J Psychiatry. 2010;167(3):341-349.
Raz A, Zhu H, Yu S, et al. Neural substrates of self-regulatory control in children and adults with Tourette syndrome. Can J Psychiatry. 2009;54(9):579-588.