Plasma amino acid levels discriminate between control subjects and mildly depressed elderly women.

Background And Aims: Depression is the most common of all psychiatric disorders and the role of amino acid transmitters in this pathology has been recently studied. We undertook this study to investigate if the plasma levels of L-arginine, L-citrulline, L-glutamic acid, L-glutamine, L-asparagine and other amino acids, the L-citrulline/L-arginine and the L-tyrosine/L-phenylalanine ratios, and the nitrite levels are modified in mildly depressed women and if such changes are related to olfactory dysfunction.

Methods: Plasma samples were obtained from elderly female subjects (n = 21) with mild depression and (n = 48) controls.