Plasma tryptophan levels and tryptophan/neutral amino acid ratios in obsessive-compulsive patients with and without depression

Laura Bellodi, Stefano Erzegovesi, Laura Bianchi, Valentina Lucini, Roberta Conca, Adelio Lucca

Research output: Contribution to journalArticle


We have studied fasting plasma tryptophan (TRP) levels and tryptophan/large neutral amino acid (TRP/LNAA) ratios in 12 patients with obsessive-compulsive disorder (OCD) and 12 patients with OCD and a coexisting current diagnosis of major depressive disorder (OCD-MDD). Assessments were made at baseline and after 6 weeks of treatment with fluvoxamine. OCD-MDD patients had significantly lower baseline TRP levels and TRP/LNAA ratios than OCD patients. After 6 weeks of fluvoxamine treatment, OCD-MDD patients had significant increases in plasma TRP and TRP/LNAA ratio, whereas OCD patients had non-significant decreases. Our data suggest that a major depressive syndrome could be a state variable affecting the changes in plasma TRP and TRP/LNAA ratio in OCD patients.

Original languageEnglish
Pages (from-to)9-15
Number of pages7
JournalPsychiatry Research
Issue number1
Publication statusPublished - Mar 3 1997



  • amino acids
  • fluvoxamine
  • serotonin
  • tryptophan

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Biological Psychiatry
  • Psychology(all)

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