[Reduced serotonin levels are predisposing to violence. A simple blood test predicts dangerous character]

Deficient serotonergic function in the brain is associated with a risk of impulsive violence. The level of serotonergic function can be assessed indirectly in several ways: 1. determination of CSF (cerebrospinal fluid) content of the serotonin metabolite 5-HIAA (5-hydroxyindoleacetic acid); 2. determination of the plasma level of the amino acid tryptophan, the serotonin precursor (passage of tryptophan into the brain is dependent on the ratio of tryptophan to other competing amino acids); 3. analysis of platelet monoamine oxidase content, a putative correlate of serotonergic capacity in the brain; 4. by determining response to an OGTT (oral glucose tolerance test), another putative correlate of serotonergic function.