Objectively validated models of the depressed suicide are lacking. Early observations that electrodermal hyporeactivity was strongly related to suicide in depression required an untraditional statistical approach that was applied on materials from published materials with between themselves totally confirming results.

A plausible explanation model of the relationship had to be developed.

The aims were to investigate the nature of electrodermal hyporeactivity and its possible causes and connections to other suicide relevant factors and to formulate a coherent model of the depressed suicide.

Published materials with in- and outpatients (in total > 900 patients) comprising follow-up of suicide and tests of habituation of the electrodermal response were analysed. Symptomatology, gender, age and other variables were considered and so were knowledge and theories from other scientists.

The apparent loss of or considerably reduced specific electrodermal orienting (curiosity) responses in future depressed suicide victims showed clear relationships to and clear independence of considered important suicidal factors.

Loss of specific orienting responses indicates loss of hippocampal CA3 plasticity. CA3 areas are early and centrally positioned in the information processing of neocortical sensory input supporting the hypothesis of a particular neuropsychological dysfunction disabling normal cognitive and emotional curiosity reactions to everyday events. It is proposed that this dysfunction may make the depressed person ready to leave the everyday life and fearless of imminent pain – a loss of two important barriers against suicide.

It seems righteous to propose this basically objectively validated model as a plausible explanation of the depressed suicide.

The author has not supplied his declaration of competing interest.