A growing body of literature increasingly supports the notion that serotonergic dysfunction may play a role in violent behavior. These findings come from animal and clinical research that probes serotonin activity through selective animal breeding techniques, central nervous system measures of serotonin, and now the indirect assessment of central serotonin function by using whole blood serotonin. In this study, 20 men arrested for murder and referred for a mental evaluation provided blood samples to measure their whole blood serotonin. The results from these men were compared with those of a 93-person reference group. Statistical analysis confirmed an increased level of whole blood serotonin in the pretrial murder defendants. The murder defendants' mean blood serotonin level was 0.41 SD higher than the reference group's. This study also found elevated whole blood serotonin among men who self-reported at least one episode of fire setting or juvenile arrest.
