Biologic studies of suicide in schizophrenia

Abnormal serotonergic function has been reported in schizophrenia, depression, and suicide. Decreased levels of the serotonin (5-HT) metabolite 5-hydroxyindoleacetic acid have been found in the cerebrospinal fluid of some patients with suicidal behavior. Decreased binding to 5-HT2A receptors in the prefrontal cortex has been reported in patients with schizophrenia, but varying results have been recorded in suicide victims. 5-HT1A receptor binding and 5-HT transporters may also be altered in suicidal and nonsuicidal patients with schizophrenia. Abnormalities have also been reported in the hypothalamo-pituitary-adrenal (HPA) axis, and there is evidence that schizophrenic patients have increased plasma cortisol output. It is interesting to note that clozapine, an antipsychotic that reduces suicidality, binds to 5-HT2A receptors and decreases cortisol output. Normalization of the interaction between the HPA axis and serotonergic function may therefore be important in reducing suicidality.