Repetition of suicide attempts across episodes of severe depression. Behavioural sensitisation found in suicide group but not in controls.

BACKGROUND: Those who die by suicide and suffer from depression are known to have made more suicide attempts during their life-span as compared to other people with depression. A behavioural sensitisation or kindling model has been proposed for suicidal behaviour, in accordance with a sensitisation model of depressive episodes. The aim of the present study was to test such a model by investigating the distribution of initial and repeated suicide attempts across the depressive episodes in suicides and controls with a unipolar severe depression.
METHOD: A blind record evaluation was performed of 80 suicide victims and controls admitted to the Department of Psychiatry between 1956 and 1969 and monitored to 2010. The occurrence of initial and repeated suicide attempts by order of the depressive episodes was compared for suicides and controls.
RESULTS: The risk of a first suicide attempt decreased throughout the later episodes of depression in both the suicide group (p < .000) and control group (p < .000). The frequencies of repetition early in the course were actually higher in the control group (p < .007). After that, the risk decreased in the control group, while the frequencies remained proportional in the suicide group. At the same time, there was a significantly greater decreased risk of repeated attempts during later episodes in the control group as compared to the suicide group (p < .000). The differences were found despite a similar number of episodes in suicides and controls.
CONCLUSION: Repeated suicide attempts in the later episodes of depression appear to be a risk factor for suicide in severe depression. This finding is compatible with a behavioural sensitisation of attempts across the depressive episodes, which seemed to be independent of a corresponding kindling of depression.