Plasma L-tryptophan depletion and aggression.

There is a well-established relationship between aggression and lowered serotonin neuro-transmission. Recently developed methodologies for manipulating L-tryptophan levels (and brain serotonin) have been applied to human laboratory studies of aggression. Collectively, these studies provide further evidence for the serotonin-aggression relationship. Two important findings have been made recently: (1) subsets of individuals (e.g., persons self-rating high on aggressive or hostility scales) may differ in their susceptibility to aggression produced through plasma tryptophan depletion; and (2) alcohol in combination with L-tryptophan depletion has an additive effect on aggression. All previous studies have been conducted with men. Extending these studies to women appears to be the much-needed next step given that serotonergic levels appear to vary both as a function of the menstrual cycle phase and menstrual symptomatology.