title: The Amygdala's Neurochemical Ratios after 12 Weeks Administration of 20 mg Long-acting Methylphenidate in Children with Attention Deficit and Hyperactivity Disorder: A Pilot Study Using (1)H Magnetic Resonance Spectroscopy.
abstract: OBJECTIVE
  Recent pediatric studies have suggested a correlation between decreased amygdala volume and attention deficit and hyperactivity disorder (ADHD) symptoms, including the emotional dysregulation. To investigate the hypothesis that medication treatment of ADHD specifically improves amygdala function, we used (1)H magnetic resonance spectroscopy (MRS) to study the effect of 12 weeks of treatment with daily 20 mg long-acting methylphenidate on the Glu/Cr, NAA/Cr, Cho/Cr, and mI/Cr ratios in the amygdala of medication-naïve children with ADHD.
  
  
  METHODS
  This was a prospective study, using a pre- and post-test design, on a single group of 21 children (average age 8.52 years, 17 males and 4 females) diagnosed with ADHD. Low Time Echo MRS scans sampled voxels of interest (1.5×1.5×2.0) from both the right and left amygdala.
  
  
  RESULTS
  There was significant clinical improvement after 12 weeks of treatment with 20 mg long-acting methylphenidate. On 1H MRS, there were no statistical significant differences of NAA/Cr ratio, Cho/Cr ratio, mI/Cr ratio before and after 12 weeks administration of 20 mg long-acting methylphenidate both in the right and left amygdala. In addition, Glu/Cr ratio decreased 14.1% in the right amygdala (p=0.029) and 11.4% in the left amygdala (p=0.008). Standardized mean effect sizes ranged from 0.14-0.32.
  
  
  CONCLUSIONS
  The findings are consistent with the possibility that hyperglutamatergic processes in the amygdale are related to the hyperactive-impulsive symptoms of ADHD.
authors.affiliation: Child and Adolescent Psychiatry Division, Department of Psychiatry, University of Indonesia, Jakarta, Indonesia. ; Consultation-Lialison Psychiatry Division, Department of Psychiatry, University of Indonesia, Jakarta, Indonesia.
authors.forename: Tjhin
authors.initials: T
authors.lastname: Wiguna
authors.affiliation: Departments of Psychiatry and Pediatrics, University of Hawai'i John A. Burns School of Medicine, Honolulu, USA.
authors.forename: Anthony Paul Sison
authors.initials: AP
authors.lastname: Guerrero
authors.affiliation: Consultation-Lialison Psychiatry Division, Department of Psychiatry, University of Indonesia, Jakarta, Indonesia.
authors.forename: Sasanto
authors.initials: S
authors.lastname: Wibisono
authors.affiliation: Department of Pediatrics, University of Indonesia, Jakarta, Indonesia.
authors.forename: Sudigdo
authors.initials: S
authors.lastname: Sastroasmoro
keywords: Amygdala; Attention deficit and hyperactivity disorder; Glutamatergic neurotransmission; Long-acting methylhenidate; Magnetic resonance spectroscopy