The Impact of Malnutrition on the Peripheral Serotoninergic System in Anorexia Nervosa: A Systematic Review

Objective: Anorexia nervosa is a severe pathology often associated with malnutrition. It is known that starvation could result in various anxious and depressive symptoms, often mentioned in eating disorders. Indeed, a lowering of plasma tryptophan through restrictive behaviours could cause a decrease in brain serotonin synthesis and give rise to these symptoms. The aim of this article was to review studies assessing plasma tryptophan and blood serotonin in anorexia nervosa, peripheral markers of the serotoninergic system. Method: A systematic computerized search was performed in Medline for all studies published between 1980 and 2012. A total of 9 studies for tryptophan and 5 studies for serotonin were reviewed for their methods, protocols and results. Results: The characteristics of sample populations and studies protocols are very heterogeneous. Nonetheless, most studies find that during the acute phase of anorexia nervosa plasma tryptophan is lowered but not blood serotonin. Discussion: Further research with longitudinal design and larger samples is needed to confirm these data. Peripheral serotoninergic markers could be a promising and non invasive way to explore how malnutrition really affects the serotoninergic system.