Case study: Caudate glutamatergic changes with paroxetine persist after medication discontinuation in pediatric OCD

Proton magnetic resonance spectroscopy (H-1-MRS) was used to examine glutam atergic (Glx) abnormalities in the caudate nucleus in pediatric obsessive-c ompulsive disorder (OCD), associated with severity of illness and response to acute (12 weeks) treatment with paroxetine. In this report, OCD symptoms improved markedly in an 8-year-old girl treated for 14 months with the sel ective serotonin reuptake inhibitor paroxetine (titrated from 10 to 40 mg/d ay). Paroxetine dose was then decreased in 10-mg decrements and discontinue d without symptom recurrence. Serial H-1-MRS examinations were acquired bef ore and after 12 weeks of paroxetine treatment (40 mg/day) and 3 months aft er medication discontinuation. A striking decrease in caudate Glx was obser ved after 12 weeks of treatment which persisted after medication discontinu ation. These data provide further support for a reversible glutamatergicall y mediated dysfunction of the caudate nucleus in OCD that may serve as a pa thophysiological and treatment response marker.