TRYPTOPHAN DEPLETION, EXECUTIVE FUNCTIONS, AND DISINHIBITION IN AGGRESSIVE, ADOLESCENT MALES

Low serotonin has been associated with aggressive behavior and impulsi vity Executive functions (cognitive abilities involved in the initiati on/maintenance of goal attainment) have also been related to aggressio n. We tested whether dietary depletion of tryptophan, the amino acid p recursor of serotonin, would increase disinhibition (impulsivity) in a ggressive male adolescents. Cognitive-neuropsychological variables pre dictive of disinhibition were explored. Stable aggressive and nonaggre ssive adolescent men received balanced and tryptophan-depleted amino a cid mixtures separately (counterbalanced, double-blind), Commission er rors on a go/no-go learning task (i.e.,failures to inhibit responding to stimuli associated with punishment/nonreward) measured disinhibitio n. Aggressive adolescent males made move commission errors as compared to nonaggressives. Lower executive functioning was significantly rela ted to commission errors over and above con conventional memory abilit ies. Tryptophan depletion had no effect on commission errors in the ag gressive adolescents, possibly because of a ceiling effect. (C) 1998 A merican College of Neuropsychopharmacology. Published by Elsevier Scie nce Inc.