title: Serum BDNF levels before treatment predict SSRI response in depression.
abstract: OBJECTIVE
  The "neurotrophin hypothesis" of depression posits a role of brain-derived neurotrophic factor (BDNF) in depression, although it is unknown whether BDNF is more involved in the etiology of depression or in the mechanism of action of antidepressants. It is also unknown whether pre-treatment serum BDNF levels predict antidepressant response.
  
  
  METHODS
  Thirty un-medicated depressed subjects were treated with escitalopram (N=16) or sertraline (N=14) for 8 weeks. Twenty-five of the depressed subjects completed 8 weeks of antidepressant treatment and had analyzable data. Twenty-eight healthy controls were also studied. Serum for BDNF assay was obtained at baseline in all subjects and after 8 weeks of treatment in the depressed subjects. Depression ratings were obtained at baseline and after 8 weeks of treatment in the depressed subjects.
  
  
  RESULTS
  Pre-treatment BDNF levels were lower in the depressed subjects than the controls (p=0.001) but were not significantly correlated with pre-treatment depression severity. Depression ratings improved with SSRI treatment (p<0.001), and BDNF levels increased with treatment (p=0.005). Changes in BDNF levels were not significantly correlated with changes in depression ratings. However, pre-treatment BDNF levels were directly correlated with antidepressant responses (p<0.01), and "Responders" to treatment (≥ 50% improvement in depression ratings) had higher pre-treatment BDNF levels than did "Non-responders" (p<0.05).
  
  
  CONCLUSIONS
  These results confirm low serum BDNF levels in un-medicated depressed subjects and confirm antidepressant-induced increases in BDNF levels, but they suggest that antidepressants do not work simply by correcting BDNF insufficiency. Rather, these findings are consistent with a permissive or facilitatory role of BDNF in the mechanism of action of antidepressants.
authors.affiliation: Department of Psychiatry, University of California, San Francisco School of Medicine, San Francisco, CA 94143, United States. Owen.Wolkowitz@ucsf.edu
authors.forename: Owen M
authors.initials: OM
authors.lastname: Wolkowitz
authors.forename: Jessica
authors.initials: J
authors.lastname: Wolf
authors.forename: Wendy
authors.initials: W
authors.lastname: Shelly
authors.forename: Rebecca
authors.initials: R
authors.lastname: Rosser
authors.forename: Heather M
authors.initials: HM
authors.lastname: Burke
authors.forename: George K
authors.initials: GK
authors.lastname: Lerner
authors.forename: Victor I
authors.initials: VI
authors.lastname: Reus
authors.forename: J Craig
authors.initials: JC
authors.lastname: Nelson
authors.forename: Elissa S
authors.initials: ES
authors.lastname: Epel
authors.forename: Synthia H
authors.initials: SH
authors.lastname: Mellon
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D019208:Brain-Derived Neurotrophic Factor / Q000097:blood*; D015283:Citalopram / Q000627:therapeutic use*; D018592:Cross-Over Studies; D003863:Depression / Q000097:blood / Q000188:drug therapy*; D003866:Depressive Disorder / Q000097:blood / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use*; D020280:Sertraline / Q000627:therapeutic use*; D016037:Single-Blind Method; D016896:Treatment Outcome
chemical_list: D000928:Antidepressive Agents; D019208:Brain-Derived Neurotrophic Factor; D015283:Citalopram; D017367:Selective Serotonin Reuptake Inhibitors; D020280:Sertraline