Psychophysiological Study of Pain Perception in Depressed Patients With Suicidal Risk

Summary

Joiner's interpersonal theory of suicide postulates that the wish of death comes from feelings of perceived burdensomeness and thwarted belongingness. But, only people who have acquired the capability to kill themselves will attempt suicide. The acquired capability refers to a reduction of fear to death, and a higher pain tolerance. Indeed, to commit suicide involves to endure pain during the act. Thus, higher pain tolerance seems to be a necessary feature for suicidal act.

Past studies have shown higher pain threshold and tolerance in suicidal patients, whatever the stimulus was (electric, thermic or mechanical), compared to patients without suicide history. Moreover, Caceda and colleagues demonstrated higher pain threshold in recent suicide attempters (suicidal act within 72h) compared with depressed patients. Five days after the initial evaluation, pain threshold of recent suicide attempters decreased to be similar to depressed patients with suicidal ideation. Therefore, it may exist a specific state during which the pain tolerance is increased. During this "hypoalgesic state" patients with suicidal ideation could attempt suicide to get relief from suffering.

However, little is known about the specific mechanisms that are responsible for the higher pain threshold and tolerance in suicide attempters. Pain is a dynamic system that results from excitatory and inhibitory messages. The modification of one of these mechanisms could explain the higher tolerance in recent suicide attempters. Three of them are of particular interest:

1. The conditioned pain modulation (CPM) is a modulatory pain mechanism. CPM works through descending pathway that reaches the spinal cord and modulates pain processing from the first nociceptive synapse.In recent suicidal patients, an increase of the CPM could explain higher pain tolerance.
2. The "wind-up" mechanism is defined as the highest excitability of the second order nerve. Even if the stimulus remains stable, pain continuously raises. In recent suicide attempters, a reduction of this mechanism could explain higher pain tolerance.
3. The threshold of Aδ and C nociceptors. If a nociceptive fiber is less excitable than the other, it would explain higher pain threshold.

Conditions

• Major Depressive Disorder

Interventions

BEHAVIORAL

Painful stimulations of major depressive patients

All three pain mechanisms will be tested in one session lasting 1h approximately. The mechanisms are tested in the following order: 1. Aδ and C threshold 2. Wind-up 3. CPM (more details in detailed description)

BIOLOGICAL

Blood sample

The blood test is made between 2 and 24 hours before the experimental procedure. The biological collection is made to measure medications' concentration if the patient takes antiepileptics and/or lithium, and to measure complete blood count (CBC).

DIAGNOSTIC_TEST

Clinical assessment

A clinical assessment will be made by a trained researcher. (more details in detailed description)

BEHAVIORAL

Social touch

Stroking

Sponsors & Collaborators

• Clinea psychiatrie France

  collaborator UNKNOWN

• University Hospital, Montpellier

  lead OTHER

Principal Investigators

• Emilie Olie, MD-PhD · University Hospital, Montpellier

Study Design

Allocation

NA

Purpose

BASIC_SCIENCE

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Max Age

65 Years

Sex

FEMALE

Healthy Volunteers

No

Timeline & Regulatory

Start

2020-11-25

Primary Completion

2024-02-21

Completion

2024-02-21

Countries

• France

Study Locations