Noradrenergic function and HPA axis dysregulation in suicidal behaviour.

Noradrenergic and HPA axis dysregulation may play a role in suicide risk. Studies of suicide risk have not found consistent relationship to the noradrenaline metabolite 3-methoxy-4-hydroxphenylglycol (MHPG) in the cerebrospinal fluid (CSF). Non-suppression in the dexamethasone test (DST) has been associated with increased risk of suicide in depressed patients. The study sample consisted of 51 mood disorder inpatients admitted to the Department of Psychiatry at the Karolinska University Hospital between 1980 and 2000. Patients underwent lumbar punction and DST and were followed up for the cause of death. The hypothesis was that both CSF MHPG and HPA axis dysregulation are associated with suicidal behaviour. Nine suicide victims had significantly lower CSF MHPG and baseline plasma cortisol than survivors. Using both CSF MHPG and baseline cortisol in ROC analysis for suicide prediction, the positive predictive value was 44% and the area under the curve was 0.88. In conclusion, lower CSF MHPG was associated with suicide risk. Furthermore these results suggest that combined measures of noradrenergic system and HPA axis function may offer better prediction of suicide risk.