Kynurenine pathway in major depression: Evidence of impaired neuroprotection

Aye Mu Myint, Yong Ku Kim, Robert Verkerk, Simon Scharpé, Harry Steinbusch, Brian Leonard

    Research output: Contribution to journalArticlepeer-review

    440 Citations (Scopus)


    The neurodegeneration hypothesis proposed major depression as a consequence of the imbalance between neuroprotective and neurodegenerative metabolites in the kynurenine pathway. To test the hypothesis, plasma tryptophan and kynurenine pathway metabolites were studied in 58 patients with major depression and 189 normal controls. The mean tryptophan breakdown index was higher (p = 0.036), and mean kynurenic acid concentration and mean neuroprotective ratios were lower, in depressed patients (p = 0.003 and 0.003, respectively). In receiver operating characteristic analysis, the kynurenic acid concentrations and the neuroprotective ratio showed clear discrimination between depressed patients and controls with area under the curve 79% and 76.3% respectively. The neuroprotective ratio did not change after treatment in those with repeated episodes of depression but it increased significantly (p = 0.044) in those with first episodes. The results suggested that the reduction in neuroprotective markers, which indicated an impaired neuroprotection, might play an important role in pathophysiology of major depression.

    Original languageEnglish
    Pages (from-to)143-151
    Number of pages9
    JournalJournal of Affective Disorders
    Issue number1-2
    Publication statusPublished - 2007 Feb


    • Kynurenic acid
    • Major depression
    • Neuroprotection
    • Neuroprotective ratio

    ASJC Scopus subject areas

    • Clinical Psychology
    • Psychiatry and Mental health


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