German and Swedish researchers found that blood pressure, blood circulation and activity in the sweat glands of the fingers can reveal if a person is suicidal. (Agencies)
"The results are so strong that I'm astonished. We can determine very accurately whether a person risks committing suicide, which can revolutionize suicide prevention," said Lars-Hakan Thorell, associate professor in experimental psychiatry at Linkoping University in Sweden, one of the researchers behind the study.
In the study, 783 depressed in-patients in Germany were tested for hypo reactivity reduced ability to react to various stimuli.
A suicidal depressed person reacts differently to environmental changes, compared to a healthy person.
The result confirms previous research stating that there is a strong correlation between hypo reactivity and suicide in depressed people.
The test found that hypo reactivity was present in up to 97 percent of depressed patients who later committed suicide, compared to just 2 per cent of the depressed patients who were not hypo reactive.
The study also found no relation between the severity of depression and hypo reactivity.
"It indicates a certain per cent, even if the normal population can have this neurophysical disorder. Everyone who has it is not suicidal - but almost all suicidal, depressed patients have it," Thorell said.
Hypo reactivity was most prevalent in the bipolar patients. Of 126 patients, 80.2 percent were affected, compared to 67.3 percent of the depressed patients and 58.5 percent of those with other diagnoses.
The study also shows that people with recurrent depression run a risk of becoming hypo reactive at some later point in life.
Hypo reactivity can be measured by the test person listening to a pattern of tones, while the body's reactions are measured via sensors on the fingers. The first time they hear a tone, virtually all people react. This is a general orientation reaction which occurs automatically. But when the tone is heard again, the reaction decreases among some people, the hypo reactive.
"A depressed person has a biological inability to care about the surroundings, while a healthy person continues to react," Thorell said.
The study was published in the Journal of Psychiatric Research.
German and Swedish researchers found that blood pressure, blood circulation and activity in the sweat glands of the fingers can reveal if a person is suicidal.