title: Tryptophan depletion and risk of depression relapse: a prospective study of tryptophan depletion as a potential predictor of depressive episodes.
abstract: BACKGROUND
  This study investigated the relationship between depressive symptom response during tryptophan depletion and future depressive episodes.
  
  
  METHODS
  Twelve subjects with prior major depressive episodes in remission and medication-free for > or =3 months (patients), and 12 matched healthy (control) subjects received two tryptophan depletion tests 1 week apart. During follow-up the Hamilton Depression Rating Scale was administered weekly for 1 month, monthly for 3 months, and once at 6 and 12 months.
  
  
  RESULTS
  With results from both tests, tryptophan depletion has a sensitivity of 78%, specificity of 80%, positive predictive value of 70%, and negative predictive value of 86% to identify future depressive episodes. Survival analysis shows that mood response to tryptophan depletion reliably predicts major depressive episodes during the follow-up year (r =.2725, p =.014).
  
  
  CONCLUSIONS
  Tryptophan depletion may be clinically useful in identifying individuals at risk for future major depressive episodes.
authors.affiliation: Department of Psychiatry, College of Medicine, The University of Arizona Health Sciences Center, Tucson 85724, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Moreno
authors.forename: G R
authors.initials: GR
authors.lastname: Heninger
authors.forename: C A
authors.initials: CA
authors.lastname: McGahuey
authors.forename: P L
authors.initials: PL
authors.lastname: Delgado
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000378:metabolism* / Q000628:therapy; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D012720:Severity of Illness Index; D014364:Tryptophan / Q000172:deficiency*
chemical_list: D014364:Tryptophan