title: Cortical inhibitory and excitatory correlates of depression severity in children and adolescents.
abstract: OBJECTIVE
  Neurophysiologic correlates of depression severity potentially have great utility in diagnosis and treatment planning. Transcranial magnetic stimulation (TMS) measures of cortical inhibition and excitability have shown promise as biomarkers in psychiatry, but no prior work has examined correlates of illness severity in pediatric mood disorders. This study sought to examine the relationship between depression severity and TMS measures of cortical inhibition and excitability in children and adolescents.
  
  
  METHODS
  Twenty-four depressed and 22 healthy control youth underwent TMS testing (cortical silent period [CSP], short-interval intracortical inhibition at 2-ms and 4-ms interstimulus intervals (ISIs) [SICI-2,-4], resting motor threshold [RMT] and intracortical facilitation at 10-, 15-, and 20-ms ISIs [ICF-10,-15,-20]). Symptom severity was assessed with the Quick Inventory of Depressive Symptomatology (QIDS-A17-SR) and the Children's Depression Rating Scale-Revised (CDRS-R).
  
  
  RESULTS
  In the overall sample, the following significant negative correlations were observed: CDRS-R and CSP (right hemisphere, ρ=-0.35, p=0.021); QIDS-A17-SR and CSP (left, ρ=-0.33, p=0.031; right, ρ=-0.42, p=0.004); and CDRS-R and SICI-4 (right, ρ=-0.30, p=0.042). Among healthy control participants, additional significant negative correlations were observed between QIDS-A17-SR and right ICF-10; QIDS-A17-SR and right ICF-15; and QIDS-A17-SR and left ICF-20. Among depressed participants, significant negative correlations were observed between QIDS-A17-SR and bilateral CSP; CDRS-R and bilateral ICF-10; CDRS-R and bilateral ICF-15; QIDS-A17-SR and left ICF-10; and QIDS-A17-SR and bilateral ICF-15.
  
  
  CONCLUSIONS
  Small sample, potential developmental/age- and sex-related effects.
  
  
  CONCLUSIONS
  These preliminary results provide evidence for a relationship between depression severity and dysfunction in GABAergic and glutamatergic cortical processes in a pediatric population.
authors.affiliation: Department of Psychiatry and Psychology, Division of Child and Adolescent Psychiatry, Mayo Clinic, Rochester, MN, USA. Electronic address: Lewis.Charles@mayo.edu.
authors.forename: Charles P
authors.initials: CP
authors.lastname: Lewis
authors.affiliation: Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Clinical Sciences, Division of Biostatistics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Nakonezny
authors.affiliation: Temerty Centre for Therapeutic Brain Intervention, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Stephanie H
authors.initials: SH
authors.lastname: Ameis
authors.affiliation: Department of Psychiatry and Psychology, Division of Child and Adolescent Psychiatry, Mayo Clinic, Rochester, MN, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Vande Voort
authors.affiliation: Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Mustafa M
authors.initials: MM
authors.lastname: Husain
authors.affiliation: Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA; Children's Medical Center of Dallas, Dallas, TX, USA.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Emslie
authors.affiliation: Temerty Centre for Therapeutic Brain Intervention, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Zafiris J
authors.initials: ZJ
authors.lastname: Daskalakis
authors.affiliation: Department of Psychiatry and Psychology, Division of Child and Adolescent Psychiatry, Mayo Clinic, Rochester, MN, USA.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Croarkin
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D003863:Depression / Q000175:diagnosis / Q000503:physiopathology*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D009433:Neural Inhibition / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation
keywords: Child and adolescent depression; Cortical inhibition; GABA; Glutamate; Intracortical facilitation; Transcranial magnetic stimulation