Proton spectroscopic imaging of the thalamus in treatment-naive pediatric obsessive-compulsive disorder

Background: Neurobiological abnormalities in rite thalamus, particularly th e dorsomedial nucleus of the thalamus, are believed to be involved in the p athophysiology of obsessive-compulsive disorder. Although obsessive-compuls ive disorder commonly arises in childhood and adolescence, no prior study h as examined the thalamus in pediatric obsessive-compulsive disorder patient s. Methods: In this study, N-acetyl-aspartate, a putative marker of neuronal v iability, creatine/phosphocreatine, and choline levels were measured in the lateral and medial subregions of the left and right thalami using a multis lice proton magnetic resource spectroscopic imaging sequence in 11 treatmen t-naive, nondepressed obsessive-compulsive disorder outpatients, 8-15 years old, and 11 case-matched control subjects. Results: A significant reduction in N-acetyl-aspartate/choline and N-acetyl -aspartate/(creatine/phosphocreatine + choline) was observed in both the ri ght and left medial thalami in obsessive compulsive disorder patients compa red with control subjects. The N-acetyl-aspartate/choline and N-acetyl-aspa rtate/(creatine/phosphocreatine + choline) levels did nor differ significan tly between case-control pairs in either rite left or the right lateral tha lamus. Reduction in N-acetyl-aspartate levels in the left menial thalamus w as inversely correlated with increased obsessive-compulsive disorder sympto m severity. Conclusions: These findings provide new evidence of localized functional ne urochemical marker abnormalities ill the thalamus in pediatric obsessive-co mpulsive disorder, Our results must be considered preliminary, however, giv en the small sample size. Biol Psychiatry 2000, 47, 174-182 (C) 2000 Societ y of Biological Psychiatry.