Previous findings suggested that electrodermal hyporeactivity has a high sensitivity (up to 97%) and high raw specificity (up to 98%) for suicide.

To evaluate prevalence, sensitivity and specificity of electrodermal hyporeactivity for suicide and suicide attempt, with and without death intent and with violent method or not, in adult patients with a primary diagnosis of depression.

At each study site at least 100 patients with a primary diagnosis of depression, also in remission, will be recruited. Depressive symptomatology will be evaluated through the Montgomery-Asberg Depression Scale. Previous suicide attempts will be registered and the death intent of the worst attempt will be rated according to the first eight items of the Beck Suicide Intent Scale. The risk of suicide will be assessed according to rules and traditions at the centre. The EDOR Test (ElectroDermal Orienting Reactivity) will be performed. Two fingers are put on gold electrodes. Through headphones a moderately strong tone is presented now and then during the test. Sensors located within the electrodes are able to register the electrodermal response to those tones, measuring the skin conductance (i.e. electrodermal activity from sweat gland activity). Each patient will be followed up for one year for actions of intentional self-harm that require medical care and for suicide. The death intent will also be rated.

It is expected that the EDOR test detects a previously unknown neuropsychological dysfunction that is independent of the depressive state and can predict suicidality with a high sensitivity and specificity.