In a group of medication-free out-patients suffering from depression and/or panic disorder we investigated the interdependence between psychological parameters such as aggression and biochemical parameters such as serotonin and tryptophan. We compared the findings in the patient group with a reference group. In the group of patients as a whole negative correlations were observed between the concentration of serotonin in platelets and depression and with hostility and aggression against others. Serotonin in plasma and tryptophan correlated negatively with hostility. The findings support the suggested link between aggression and depression with a low functioning serotonergic system.
