A double blind, randomized cross-over trial of tyrosine treatment on cognitive function and psychological parameters in severe hospitalized anorexia nervosa patients

Background: Anorexia nervosa (AN) is characterized by self-induced malnutrition, affecting body image, mood, cognition and survival. Tyrosine, an essential amino acid is the precursor of catecholamines. The use of tyrosine to treat AN is based on experiments on diet restricted mice, in which it increased food consumption, improved cognitive function and elevated brain catecholamines. We evaluated the effect of oral tyrosine administration on the cognition and emotional state of patients with AN. We hypothesized that tyrosine may improve cognitive function without changing body weight, thus “kick-start” nutritional rehabilitation. Methods: 19 female hospitalized patients with chronic AN were supplemented with L-tyrosine (100 mg/kg/day)/ placebo capsules for a three-week period in a double blind, randomized, cross-over study. Participants were evaluated cognitively and psychologically. Results: Tyrosine shortened reaction time and test duration in memory tasks and improved depressive mood. No side effects were noted with the use of tyrosine. Conclusions: Tyrosine may improve cognitive function and psychological traits associated with AN.