A German-Swedish study evaluated 783 depressed inpatients in Germany for hyporeactivity — a 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 hyporeactivity and suicide in depressed people.
“The results are so strong that I’m astonished,” said Lars-Håkan Thorell, associate professor in experimental psychiatry at Linköping University.
“We can determine very accurately whether a person risks committing suicide, which can revolutionize suicide prevention.”
Hyporeactivity 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 amongst some people: the hyporeactive.
The study is published in the Journal of Psychiatric Research.
Researchers found that hyporeactivity was present in up to 97 percent of depressed patients who later committed suicide, compared to just 2 percent of the depressed patients who were not hyporeactive. But the study also shows there is no relation between the severity of depression and hyporeactivity.
Thorell pointed out that the findings indicate that some of the normal population can have this neurophysical disorder.
“Everyone who has it is not suicidal — but almost all suicidal, depressed patients have it.”
Hyporeactivity 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 hyporeactive at some later point in life.
“It was probably the case that certain nerve cells in the hippocampus are damaged by depressions and negative stress,” Thorell said.
“A depressed person has a biological inability to care about the surroundings, while a healthy person continues to react.”
Source: Linköping University