Abnormalities in metabolite concentrations in tourette's disorder and obsessive-compulsive disorder—A proton magnetic resonance spectroscopy study

Introduction Abnormal glutamatergic transmission in cortico-striato-thalamo-cortical (CSTC) circuits is thought to be involved in the pathophysiology of Tourette's disorder (TD) and obsessive-compulsive disorder (OCD). Using proton magnetic resonance spectroscopy, the current study aimed to investigate regional concentrations of glutamatergic compounds in TD and OCD patients in comparison to healthy control subjects (HC). Material and methods Twenty-three TD patients, 20 OCD patients and 22 HC were included. Short echo-time single-voxel 3T MRS was obtained from dorsal anterior cingulate cortex (dACC) and midline bilateral thalamus. Results The 3-group comparison showed a significant difference in choline concentration in the thalamus. Thalamic choline was highest in OCD patients, showing a significant difference with TD, and a trend compared to HC (post-hoc analyses). Glutamine in dACC correlated negatively with tic severity scores in TD patients, while glutamate in thalamus correlated positively with anxiety severity scores in OCD patients. Conclusions These findings suggest subtle differences in metabolites in CSTC areas between TD and OCD. Alterations of choline concentrations seem to be both regional (only in thalamus, not in dACC) and disease specific in OCD pathology. The findings need replication in larger groups, but encourage further research into glutamatergic metabolites in TD and OCD.