Can Simple Finger Test Predict Suicide Risk?

People affected by depression-related mental disorders have increased chances of attempting and committing suicide. Examples of these disorders include major depression, persistent depressive disorder (dysthymia) and various forms of bipolar disorder. In a study published in September 2013 in the Journal of Psychiatric Research, a team of Swedish and German researchers examined the usefulness of a simple bodily reaction to sensory stimulation as a predictor for suicide risks in people with a depression-related illness. The members of this team concluded that the vast majority of depressed and bipolar individuals have this reaction, which can therefore act as a warning sign for suicidal thoughts and behaviors. “The results are so strong that I’m astonished”, said Lars-Håkan Thorell, associate professor in experimental psychiatry at Linköping University, one of the researchers behind the study. “We can determine very accurately whether a person risks committing suicide, which can revolutionise suicide prevention.”

Depression-Related Illness and Suicide

Suicide and depression-related mental disorders are two of the most frequently encountered serious health concerns in the U.S. Current figures indicate that suicide ranks as Americans’ eighth-most common cause of death. At the same time, roughly 6 percent to 12 percent of all people in the U.S. experience bouts of major depression or some other depressive disorder, while about 2.6 percent of the adult American population has symptoms of a bipolar condition such as bipolar I disorder, bipolar II disorder or cyclothymic disorder. Both depressed individuals and bipolar individuals have unusually high risks for thinking about suicide, making suicidal plans, making active suicide attempts and actually killing themselves. In many cases, the suicide-related risks associated with these depressive and bipolar disorders coexist with other known suicide risk factors such as substance abuse or addiction, a family history of mental illness and/or suicide, unusually high levels of impulsive behavior and exposure to violence within the home.

An Unusual Body Reaction Called Electrodermal Hyporeactivity

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. “A depressed person has a biological inability to care about the surroundings, while a healthy person continues to react,” Thorell said.

New Findings

In the study published in the Journal of Psychiatric Research, a multinational research team used an examination of 783 German adults hospitalized for depression-related mental disorders to determine whether the presence of electrothermal hyporeactivity can help predict suicide risks in a person diagnosed with a depressive illness or a bipolar illness. The team decided to perform this examination because previous research efforts had shown a potential connection between hyporeactivity in depressed individuals and increased rates for suicidal thoughts and actions. After reviewing their data, the researchers found that as many as 97 percent of people with a depression-related illness who commit suicide have electrothermal hyporeactivity. In stark contrast, only roughly 2 percent of people with a depression-related illness commit suicide when unaffected by electrothermal hyporeactivity. The strongest connections between hyporeactivity and suicide are found in people diagnosed with a bipolar disorder, and particularly strong connections also exist in people diagnosed with major depression. In addition, the researchers concluded that people initially unaffected by hyporeactivity who experience repeated bouts of depression have increasing chances of eventually developing hyporeactivity over time.

Significance and Considerations

The authors of the study note that a depression- and stress-related change in brain function probably accounts for the presence of electrothermal hyporeactivity in affected individuals. The biological effects of this brain change apparently make it difficult for depressed people to maintain interest in their local environment and continue to respond to repeated sensory stimulation. The study’s authors also found that hyporeactivity can occur just as often in mildly or moderately depressed individuals as it occurs in severely depressed individuals at clear risk for killing themselves. In practical terms, this means that hyporeactivity alone cannot reliably indicate a depressed person’s overall suicide risks. However, even with this fact in mind, the extremely high rate of hyporeactivity in suicidally depressed people makes the presence of this body reaction clearly useful as suicide predictor.

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