Dietary tryptophan depletion according to body weight - A new treatment option in acute mania?

Department of Child and Adolescent Psychiatry and Psychotherapy, Goethe University of Frankfurt/Main, Deutschordenstr. 50/Building 92, 60528 Frankfurt am Main, Germany.
Medical Hypotheses (Impact Factor: 1.07). 11/2008; 72(1):47-8. DOI: 10.1016/j.mehy.2008.06.046
Source: PubMed


Decreased neurotransmission of serotonin (5-HT) was shown to be related to the development of depressive symptoms, whereas recent preliminary evidence suggests that acute mania may be related to a hyperserotonergic state. The reduction of central nervous 5-HT synthesis achieved by a new modification of the dietary rapid tryptophan depletion technique, with the relevant amino acids dosed according to body weight, is hypothesized by the authors to be a further option of treatment during acute mania, in particular in view of a decrease in adverse reactions, a reduced amount of amino acids needed for sufficient depletion, but also improved tolerability. However, ethical issues may limit such studies investigating this relationship in acutely manic patients, in particular in view of informed consent.

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    • "A modified mixture, ATD Moja-De, involves a body weight adapted administration of amino acids and lower concentration of methionine relative to conventional mixtures, which makes it less nauseating in humans. Its use has proven to be a safe and effective method of TRP depletion even in children and adolescents [9], [10], [11], [12], [13], [14], [15]. It has been shown that ATD Moja-De significantly lowers influx of TRP into the brain in humans [16], but its specific effect on brain 5-HT has not yet been established, which was the aim of this study. "
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    ABSTRACT: Acute tryptophan depletion (ATD) is a method of lowering brain serotonin (5-HT). Administration of large neutral amino acids (LNAA) limits the transport of endogenous tryptophan (TRP) across the blood brain barrier by competition with other LNAAs and subsequently decreases serotonergic neurotransmission. A recent discussion on the specificity and efficacy of the ATD paradigm for inhibition of central nervous 5-HT has arisen. Moreover, side effects such as vomiting and nausea after intake of amino acids (AA) still limit its use. ATD Moja-De is a revised mixture of AAs which is less nauseating than conventional protocols. It has been used in preliminary clinical studies but its effects on central 5-HT mechanisms and other neurotransmitter systems have not been validated in an animal model. We tested ATD Moja-De (TRP-) in two strains of mice: C57BL/6J, and BALB/cJ, which are reported to have impaired 5-HT synthesis and a more anxious phenotype relative to other strains of mice. ATD Moja-De lowered brain TRP, significantly decreased 5-HT synthesis as indexed by 5-HTP levels after decarboxlyase inhibition, and lowered 5-HT and 5-HIAA in both strains of mice, however more so in C57BL/6J than in BALB/cJ. Dopamine and its metabolites as well as norepinephrine were not affected. A balanced (TRP+) control mixture did not raise 5-HT or 5-HIAA. The present findings suggest that ATD Moja-De effectively and specifically suppresses central serotonergic function. These results also demonstrate a strain-specific effect of ATD Moja-De on anxiety-like behavior.
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    ABSTRACT: Reduced mean heart rate (HR) was shown to be a biophysiological marker for aggression, which in turn was proven to be related to changed serotonergic neurotransmission. A total of 16 ADHD-diagnosed boys were subjected to rapid tryptophan depletion (RTD) and a placebo in a double-blind within-subject crossover-design. Mean HR was assessed under RTD/placebo. Low impulsive patients behaving aggressively under RTD showed a lowered HR under RTD versus placebo. Diminished 5-HT functioning was associated with lowered HR and aggressive behaviour.
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