Objective: Although abnormalities of neural circuits involving the cortex, striatum, and thalamus are hypothesized to underlie Tourette's disorder, the neuronal abnormalities within components of these circuits are unknown. The purpose of this study was to examine the cellular neurochemistry within these circuits in Tourette's disorder using proton magnetic resonance spectroscopy, a method that has not previously been used in neurobiological investigations of the disorder.
Method: Proton magnetic resonance spectroscopic imaging examinations were conducted in 25 males with Tourette's disorder (age 10.9 +/- 2.0 years) and 32 male comparison subjects (age 11.5 +/- 2.7 years). Spectra from frontal cortex, caudate nucleus, putamen, and thalamus were analyzed, and N-acetylaspartate, creatine, choline, myoinositol, and glutamate + glutamine were quantified and compared between the groups.
Results: Patients with Tourette's disorder demonstrated a reduction in N-acetylaspartate and choline in the left putamen, along with reduced levels of creatine bilaterally in the putamen. In the frontal cortex, patients had significantly lower concentrations of N-acetylaspartate bilaterally, lower levels of creatine on the right side, and reduced myoinositol on the left side.
Conclusions: The results of this study suggest compromised neuronal integrity and deficits in density of neuronal and nonneuronal cells in components of the neural circuits implicated in Tourette's disorder.