title: Pretreatment cerebral metabolic activity correlates with antidepressant efficacy of vagus nerve stimulation in treatment-resistant major depression: a potential marker for response?
abstract: BACKGROUND
  Pretreatment brain activity in major depressive disorder correlates with response to antidepressant therapies, including pharmacotherapies and transcranial magnetic stimulation. The purpose of this trial was to examine whether pretreatment regional metabolic activity in selected regions of interest (ROIs) predicts antidepressant response following 12 months of vagus nerve stimulation (VNS) in 15 patients with treatment-resistant major depression (TRMD).
  
  
  METHODS
  Fluorodeoxyglucose positron emission tomography (FDG PET) was used to assess regional mean relative cerebral metabolic rate for glucose (CMRGlu) in four ROIs (anterior insular, orbitofrontal, anterior cingulate, and dorsolateral prefrontal cortices) at baseline (prior to VNS activation). Depression severity was assessed at baseline and after 12 months of VNS using the Hamilton Depression Rating Scale (HDRS), with response defined as ≥ 50% reduction in HDRS from baseline.
  
  
  RESULTS
  Baseline CMRGlu in the anterior insular cortex differentiated VNS responders (n=11) from nonresponders (n=4) and correlated with HDRS change (r=.64, p=.01). In a regression analysis, lower anterior insular cortex CMRGlu (p=.004) and higher orbitofrontal cortex CMRGlu (p=.047) together predicted HDRS change (R(2)=.58, p=.005). In a whole brain, voxel-wise analysis, baseline CMRGlu in the right anterior insular cortex correlated with HDRS change (r=.78, p=.001).
  
  
  CONCLUSIONS
  Sample size was small, limiting statistical power; patients remained on their psychiatric medications; study was open-label and uncontrolled.
  
  
  CONCLUSIONS
  This preliminary study suggests that pretreatment regional CMRGlu may be useful in predicting response to VNS in TRMD patients.
authors.affiliation: Department of Psychiatry, Washington University, St. Louis, MO, USA. cconway@wustl.edu
authors.forename: Charles R
authors.initials: CR
authors.lastname: Conway
authors.forename: John T
authors.initials: JT
authors.lastname: Chibnall
authors.forename: Sunil
authors.initials: S
authors.lastname: Gangwani
authors.forename: Mark A
authors.initials: MA
authors.lastname: Mintun
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Price
authors.forename: Tamara
authors.initials: T
authors.lastname: Hershey
authors.forename: Luis A
authors.initials: LA
authors.lastname: Giuffra
authors.forename: Richard D
authors.initials: RD
authors.lastname: Bucholz
authors.forename: Jon J
authors.initials: JJ
authors.lastname: Christensen
authors.forename: Yvette I
authors.initials: YI
authors.lastname: Sheline
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000378:metabolism*; D061218:Depressive Disorder, Treatment-Resistant / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000378:metabolism / Q000628:therapy*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D055536:Vagus Nerve Stimulation
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose