(Reuters Health) - One suicide attempt in an army unit may foreshadow attempts by other soldiers in the same unit, suggests a new study from the U.S. military.

“Clusters do occur, and if there is a suicide attempt in an Army unit there is likely to be another attempt in the unit,” said lead author Dr. Robert Ursano, of the Uniformed Services University of the Health Sciences in Bethesda, Maryland.

Suicide attempts in the U.S. Army increased dramatically during the Iraq and Afghanistan wars, and the risk might have been influenced by events within a soldier’s unit, Ursano and colleagues write in JAMA Psychiatry.

To see if factors within a unit predict the risk of future suicide attempts, the researchers analyzed data from soldiers on active duty from 2004 through 2009.

They identified 9,512 soldiers who attempted suicide during that time. Most were men, under age 29, white, educated, married and had entered the Army before age 21.

The risk that soldiers would attempt suicide increased with the number of suicide attempts in the same unit over the past year.

Compared to soldiers in units with no suicide attempts over the previous year, soldiers in units with a recent suicide attempt were 40 percent more likely to attempt suicide themselves, for example.

In units with five or more suicide attempts during the past year, the risk of another attempt was more than twice as high as in units with no attempts during the past year.

The increased risk was seen regardless of whether the soldiers had combat experience and regardless of the size of the unit. Smaller units had a greater risk, however.

The study can’t say why the risk of suicide attempts in a unit increases with the number of past suicide attempts.

Ursano told Reuters Health that it could be related to a phenomenon known as contagion, but it could also be due to stresses on the unit such as a change in leadership or whether the unit is preparing for or returning from deployment.

While the study took place among a relatively consistent group of people with jobs, health insurance and a steady income, Ursano said the findings may be true for civilians, too.

“These days, it should not be forgotten that people live in groups, communities and families,” he said.

The Israeli Defense Force tackled the issue of suicide attempts by making sure there was a culture of help-seeking, said Dr. John Mann, of the Columbia University Medical Center and the New York State Psychiatric Institute in New York City.

“We have seen in militaries - like the Israeli Defense Force - a substantial decrease in suicide rates,” said Mann, who was not involved in the new study. “We’ve seen that at a time when the suicide rates went up in the U.S. military. We can try to learn from other places about things that affect suicide rates.”

People should encourage those at risk to seek help, he said.

Ursano said one avenue for future research is to look at ways to address the risk of suicide attempts at a group level - instead of focusing on individuals.

“Think about the stresses on the community the person belongs to as well as the individual,” he said.

SOURCE: bit.ly/2uDbJJN and bit.ly/2uD47XF JAMA Psychiatry, online July 26, 2017.