Scientists link gene mutations to risk of suicide | Science| In-depth reporting on science and technology | DW | 05.02.2010
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Science

Scientists link gene mutations to risk of suicide

10,000 Germans commit suicide every year and 1 million people commit suicide annually worldwide. German researchers suggest that certain gene mutations may influence the ability to control suicidal impulses in patients

A photo of a gene

Five mutations in two genes related to nerve growth are more common among people who have attempted suicide

New research has shown that several mutations of genes involved in nerve cell formation and growth may predispose certain people suffering from depression to commit suicide.

Logo of the Max Planck Society

Research was conducted at the Max Planck Institute of Psychiatry in Munich

Scientists at the Max Planck Institute of Psychiatry in Munich hope their discovery can contribute to depression treatment methods and suicide prevention strategies. The study will be published in the journal Archives of General Psychiatry in April.

"A lot of patients have suicidal thoughts but they don't all act on it," said Elizabeth B. Binder, Ph.D, the research group leader of the project.

When a patient possesses one of these discovered genetic variations, she added, a level of control may become missing and the person may be more likely to act.

The Method

The scientists examined two genes, BDNF and NTRK2, which regulate proteins that support memory, and promote the growth and connection of nerve cells. The researchers tested 394 psychiatric patients with depression from Germany, 113 of which attempted suicide, and compared them to a similar size group of healthy participants.

The authors then replicated the study with another 744 German patients, 152 of whom attempted suicide. Finally, they studied a larger group of African Americans who all showed depressive symptoms and some of whom attempted suicide.

When the researchers compared these genes in blood samples of the depressed patients with the same genes in blood samples of the healthy patients, they discovered no difference. However, when they compared these genes in samples of those depressed patients who have attempted suicide with genes in samples of the patients who have not, five gene mutations appeared to be more common among those who have attempted suicide.

Conclusions

Researchers thus concluded that these gene variations relate specifically to suicide behavior and not depression as a whole. Furthermore, analysis showed that the risk of patients with the three more major gene variations of committing suicide increases by more than fourfold.

"Our findings from this association genetic approach now suggest that there is a predisposing relationship between this gene system and suicidal behavior," said Martin A. Kohli, a researcher in the project currently at the John P. Hussman Institute for Human Genomics, Miami, in an email interview.

Previous post mortem research of the brain, he added, consistently found lower levels of these genes in suicide victims compared to persons with other causes of death. Although a direct chemical cause for suicide is not yet known, the researchers speculate that these mutations may be contributing to disturbed brain signaling which in turn may lead to problems with impulse control.

"The goal of the study was to get further support for the implication of the role of the neurotrophic system in suicide," Binder said, and available statistics show that such support is highly necessary.

Woman sitting in the corner in a depressive state

scientists hope that the research will raise awareness for the biology of suicide and promote targeted treatment

How those at risk for suicide can benefit

According to AGUS, a support organization for suicide in Bayreuth, 10,000 Germans commit suicide every year. Statistics from the research project also state that there are roughly 10 to 20 million suicide attempts and one million actual suicides world wide each year. Among those under 31 years old, one in four deaths results from suicide.

"It's very important to understand the neurobiology of suicide behavior," Binder said, since these statistics are big and there is no real prevention strategy.

According to Kohli, this data could allow for targeting of more intense therapeutic and preventive measures in patients carrying this risk, including prescribing certain medications.

For instance, Binder added, if a person diagnosed with depression possesses this risk variant, even if the condition improves, reducing medications may still be a bad idea and the person may need to be under observation for a longer period of time.

Ultimately, "this could help decrease suicide rates," Kohli said.

Author: Alina Dain
Editor: Mark Mattox

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