People who have made a suicide attempt, less sensitive to bodily discomfort and pain than their peers who scored similar scores in the questionnaires of psychological state, but not trying to die, reported in eLife. They can longer hold my breath and keep my hand in cold water, and in addition, accurately determine the frequency of cardiac contractions.
The survival instinct does not give the animal to intentionally harm themselves. However, some people can overcome this instinct and to cause yourself physical pain or even to commit suicide. It is logical to assume that they have changed the functioning of the nervous system in such a way that they are able to ignore the discomfort signals from your own body.
This hypothesis was tested by researchers from the University of Tulsa headed by Chelsey Sahib (Sahib Khalsa). Of the participants of the project Tulsa-1000 they selected 34 patients (mean age 31 years) that not more than 5 years before this have made a suicide attempt, and 68 people of the same age, with similar performance on psychological questionnaires (Patient Health Questionnaire-9 (PHQ-9), Overall Anxiety Severity and Impairment Scale (OASIS), Drug Abuse Screening Test-10 (DAST-10), Eating Disorder Screen (SCOFF). However, the second (control) group did not try to commit suicide.
The subjects performed several tests on the breath (had sitting while holding a clip nose to inhale and not exhale as long as possible, and then evaluate their status; at the same analyzed gas composition of the first after a delay of exhalation), for cold stress (dominant hand was immersed in a container with running water at a temperature of 6 degrees Celsius and was asked to hold until it becomes unbearable), to determine the frequency of your heartbeat (you had to press the key each time when the heart of the subject, in his opinion, reduced).
In addition, volunteers were given the task alternately to listen to the feelings of the heart and the stomach (as a control task on the perception of external signals), while simultaneously recorded with functional magnetic resonance imaging the activity of various parts of their brain. One of them included the proportion of islet, one of the functions which analyze a variety of signals (including pain) from internal organs.
Those who tried to commit suicide, an average of 10 seconds longer held your breath than people in the control group (p = 0.036). They also on average 18 seconds longer withstand the action of cold water on hand (p = 0.006). In this test they had to determine the level of pain (mild, moderate, strong), and people with suicide attempts took more time to achieve each level than others. In addition, potential suicides are less accurately identified when they reduced the heart (p = 0.003–,04 depending on the test series, of which there were several).