CSF 5-HIAA, cortisol and DHEAS levels in suicide attempters.

The serotonin system and the hypothalamic-pituitary-adrenal (HPA) axis are involved in the biological vulnerability to suicidal behaviour. Altered levels of dehydroepiandrosterone (DHEA) and its sulphate ester DHEAS have been reported in neuropsychiatric conditions. The aim of this study was to investigate CSF levels of 5-Hydroxyindoleacetic acid (5-HIAA) and CSF and plasma levels of cortisol and DHEAS in 28 medication free suicide attempters and 19 healthy volunteers. Another aim was to investigate the relationship between neuroendocrine measures and childhood trauma in suicide attempters. As the study design includes a longitudinal part, we investigated whether CSF cortisol, 5-HIAA or DHEAS would predict subsequent suicide. We hypothesized higher cortisol levels in suicide attempters and lower CSF 5-HIAA levels and higher cortisol levels in suicide victims. Suicide attempters had higher CSF and plasma cortisol levels compared to healthy volunteers. Male suicide attempters had higher CSF DHEAS levels and female suicide attempters had lower CSF 5-HIAA levels compared to male and female healthy volunteers respectively. Exposure to interpersonal violence as a child showed a negative correlation with CSF cortisol/DHEAS ratio adjusted for age, gender and depression severity in a regression analysis. Suicide victims tended to have low CSF 5-HIAA and high CSF cortisol. Abused suicide victims had higher CSF cortisol compared to suicide victims with low exposure to interpersonal violence as a child. The results underlie the important role of the serotonergic system and HPA axis in suicidal behaviour and suggest that CSF DHEAS may be elevated in male suicide attempters.

Low CSF oxytocin reflects high intent in suicide attempters.

Data from animal studies suggest that oxytocin is an important modulating neuropeptide in regulation of social interaction. One human study has reported a negative correlation between CSF oxytocin levels, life history of aggression and suicidal behaviour. We hypothesized that CSF oxytocin levels would be related to suicidal behaviour, suicide intent, lifetime interpersonal violence and suicide risk. 28 medication free suicide attempters and 19 healthy volunteers participated in this cross sectional and longitudinal study. CSF and plasma morning basal levels of oxytocin were assessed with specific radio-immunoassays. The Beck Suicide Intent Scale (SIS), the Freeman scale and the Karolinska Interpersonal Violence Scale (KIVS) were used to assess suicide intent and lifetime violent behaviour. All patients were followed up for cause of death. The mean follow-up was 21 years. Suicide attempters had lower CSF oxytocin levels compared to healthy volunteers p=0.077. In suicide attempters CSF oxytocin showed a significant negative correlation with the planning subscale of SIS. CSF oxytocin showed a significant negative correlation with suicide intent, the planning subscale of SIS and Freeman interruption probability in male suicide attempters. Correlations between plasma oxytocin levels and the planning subscale of SIS and Freeman interruption probability were significant in male suicide attempters. Lifetime violent behaviour showed a trend to negative correlation with CSF oxytocin. In the regression analysis suicide intent remained a significant predictor of CSF oxytocin corrected for age and gender whereas lifetime violent behaviour showed a trend to be a predictor of CSF oxytocin. Oxytocin levels did not differ significantly in suicide victims compared to survivors. CSF oxytocin may be an important modulator of suicide intent and interpersonal violence in suicide attempters.