Biomarkers of suicide risk in psychosis

Abstract: Suicide and attempted suicide are major health problems. Approximately 1400 people die from suicide every year in Sweden and ten times more attempt suicide. Patients with schizophrenia spectrum psychosis have an increased risk of suicide and suicide rates have been suggested to be as high as 10%. Important risk factors include a prior suicide attempt and depressive disorder. Low concentrations of monoamine metabolites in cerebrospinal fluid (CSF) have been related to suicidal behavior in patients diagnosed with mood disorders. Few studies have investigated patients with schizophrenia spectrum psychosis and they suffer from small numbers of patients, short periods of follow-up and contradictory results. The main objective of this study was to investigate the long-term suicide risk in schizophrenia spectrum psychosis, whether concentrations of the CSF monoamine metabolites 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) are related to suicidal behavior and to the overall mortality. The importance of other factors influencing suicide risk such as a prior suicide attempt, gender and CSF kynurenic acid (KYNA) was also investigated. Inpatients (n=385) with schizophrenia like symptoms were lumbar punctured at admittance and followed up for a median period of 26 years. Information about prior suicide attempts was retrieved from the medical records. Causes of death were obtained from the Causes of Death Register. During the follow-up period nearly equal percentages of men (6.5 %) and women (6.9 %) died by suicide. Eighteen percent of suicide attempters and 2% of the non-attempters died by suicide. The suicide risk was almost three times higher in male attempters than in females. Thus, attempted suicide and male gender were significant risk factors for suicide. There were neither any associations between CSF concentrations of 5-HIAA and HVA, or their ratio, nor between CSF KYNA concentrations and suicide or attempted suicide. CSF 5-HIAA and HVA concentrations were not a risk factor for early death from natural causes. Patients with schizophrenia spectrum psychosis have a high long-term risk of suicide. Attempted suicide was a very important risk factor for suicide in both genders, especially in males. In contrast to patients diagnosed with mood disorders, CSF 5-HIAA and HVA concentrations were not associated with suicidal behavior in schizophrenia spectrum psychosis patients.