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Randomized Controlled Trial
. 2006 Jul;31(4):253-62.

Social behaviour and mood in everyday life: the effects of tryptophan in quarrelsome individuals

Marije aan het Rot  1 , Debbie S Moskowitz, Gilbert Pinard, Simon N Young
Affiliations
Randomized Controlled Trial

Social behaviour and mood in everyday life: the effects of tryptophan in quarrelsome individuals

Marije aan het Rot et al. J Psychiatry Neurosci. 2006 Jul.

Abstract
in English, French

Objective: We hypothesized that increasing brain serotonin in healthy individuals with high scores on 2 self-report measures of trait quarrelsomeness would reduce quarrelsome behaviours and enhance agreeable behaviours when measured ecologically using an event-contingent recording method.

Methods: We conducted a double-blind crossover study, in which participants took tryptophan (3 g/d) and placebo for 15 days each and recorded how they behaved, felt and perceived others during everyday social interactions.

Results: Tryptophan significantly decreased quarrelsome behaviours and increased agreeable behaviours and perceptions of agreeableness. Men also behaved less dominantly, whereas both men and women perceived others as more dominant.

Conclusion: Tryptophan's effects on behaviours and perceptions, while more marked in the men, were generally positive and accompanied by improved affect. Increasing serotonin in quarrelsome people may not only reduce behaviours associated with a predisposition to various mental and physical disorders but also enhance socially constructive behaviours and improve social perceptions.

Objectif: Nous avons posé en hypothèse que l'élévation de la concentration de sérotonine cérébrale chez des sujets en bonne santé qui ont des résultats élevés à deux mesures autodéclarées du caractère belliqueux réduirait les comportements belliqueux et améliorerait les comportements affables lorsqu'on les mesure écologiquement au moyen d'une méthode de consignation contingente des événements.

Méthodes: Nous avons réalisé un essai croisé à double insu pour lequel les participants ont pris du tryptophane (3 g/j) et un placebo pendant 15 jours chacun et ont consigné leur comportement, leurs sentiments et leur perception à l'égard d'autrui pendant les interactions sociales quotidiennes.

Résultats: Le tryptophane réduit considérablement les comportements belliqueux et accroît les comportements affables et les perceptions d'un caractère affable. Les hommes se sont aussi comportés de façon moins dominante tandis que les hommes et les femmes percevaient les autres comme plus dominants.

Conclusion: Même s'ils sont plus marqués chez les hommes, les effets du tryptophane sur les comportements et les perceptions ont en général été positifs et ont entraîné une amélioration de l'affect. L'élévation de sérotonine chez les personnes belliqueuses peut non seulement atténuer les comportements associés à une prédisposition à divers troubles mentaux et physiques, mais aussi améliorer les comportements socialement constructifs et les perceptions sociales.

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Figures

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Fig. 1: Affect valence during tryptophan and placebo phases of treatment (values are estimated least squares means and standard errors). The horizontal axis crosses the vertical axis at 5 to indicate the middle of the individual axes on the affect grid. Tryptophan increased the pleasantness of affect in participants who received tryptophan second (*p < 0.001).
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Fig. 2: Daily ipsatized frequencies of (a) quarrelsome, (b) agreeable and (c) dominant behaviours during tryptophan and placebo phases of treatment (values are estimated least squares means and standard errors). A description of the ipsatizing procedure can be found in the Methods section. Tryptophan decreased quarrelsomeness (*p = 0.028). In men, tryptophan also increased agreeableness (**p < 0.001) and decreased dominance (***p = 0.002).
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Fig. 3: Perceptions of (a) agreeableness and (b) dominance during tryptophan and placebo phases of treatment (values are estimated least squares means and standard errors). The horizontal axis crosses the vertical axis at 6 to indicate the middle of the individual axes on the interpersonal grid. Tryptophan increased perceived agreeableness in others in men who received tryptophan second (*p = 0.019). Tryptophan also increased perceived dominance in others (**p < 0.001).
See this image and copyright information in PMC

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