EDA (ElectroDermal Activity) is one of the most basic parameters for automatic nervous systems assessment which is controlled by sympathetic nervous system. Sympathetic nerve activity and sweating variations in the skin are regulated by environmental temperature and by central activations related to affective and cognitive states.
EDA includes tonic and phasic components.
Tonic component: is related to the slower acting activities and background characteristics of the signal (Skin Conductance Level – SCL);
Phasic component: faster changing elements of the signal that can be associated either to a stimulus (Skin Conductance Response – SCR), or be spontaneous or nonspecific.
Previous studies conducted by Thorell at Linköping University suggested that electrodermal hyporeactivity could be considered as a reliable and valid indicator to measure the risk of suicide propensity in depressed patients. Non-at-risk patients demonstrate normal reactivity, with habituation, to the tone stimuli generated by EDOR (L-H Thorell, 1987, 2009, 2013).
Neuropsychological basis of electrodermal hyporeactivity seems to lie in the hippocampus in relation with specific neurons in the CA3 areas which are link to natural evocation of orienting attention and curiosity in everyday life.
EDOR (Electro Dermal Orienting Reactivity) test
EDOR is an innovative biomarker-based device for measuring brain reactivity expressed as sweat impulses when exposing the patient to repeated and identical audio signals at irregular intervals. It analyses the momentary activation induced by the brain on the individual’s sweat glands when this one responds to EDOR’s specific audio signal.
To have more information see also http://emotra.se/en/
EUDOR-A multi-center study
In 2015 the “EUDOR-A multi center research program: A naturalistic, European Multi-Centre Clinical Study of EDOR test in adult patients with primary depression” started. It is supported by the EPA Section of Suicidology and Suicide Prevention and was born from the fruitful collaboration among many European members, with the aims to test the effectiveness and the usefulness of the EDOR Test as a support in the suicide risk assessment of depressed patients and to assess the predictive value of electrodermal hyporeactivity, measured through the EDOR Test, for suicide and suicide attempt in adult patients with a primary diagnosis of depression.
After the EDOR test a one year follow-up was performed in order to assess possible suicides, suicide attempts and depressive episodes. Here some preliminary results are shown.
Characteristics of the sample:
|Total number of patients included in the study|| 1574
– 767 (49%) inpatients
– 807 (51%) outpatients
|Number of patients with test results and clinical data at baseline||1545 (98%)|
|Prevalence of hyporeactivity at baseline||291 (19%)|
|Suicide attempters (lifetime)||582 (38%)|
|Number of patients with follow-up data||1427 (90%)|
|Suicide attempters during follow-up||80 (6%)|
- Hyporeactivity was statistically independent of gender, age, type of care, somatic diseases, being drug free or not (medical);
- Even if there is not statistical significance, hyporeactive patients have been found more at risk of suicide than reactive patients;
- A strong correlation has been found between hyporeactivity and attempted suicide life time (p 0.0000018);
- Hyporeactivity was more prevalent in patients with severe depressive episode according to ICD-10 than in all other levels of severity (p= 0.022);
- Hyporeactivity was more common in patients with bipolar disorders in most severe episodes (ICD-10) compared to all other bipolar disorders (p= 0.022) and compared to all other primary mood disorders (p= 0.0017).
A deeper statistical analysis is still ongoing.
The first Consensus Meeting of the study has been held on March, 29 2017 in Rome; the partner consortium agreed that the EDOR® could be a valid complementary tool in the suicidal risk assessment.
To know more, contact EPA- SSSP e-mail address: email@example.com