[Photo/IC]

A simple blood test to detect a chemical alteration in a single human gene linked to negative thoughts and impulses may reliably predict a person's risk of attempting suicide, U.S. researchers said Wednesday.

The discovery, described online in the American Journal of Psychiatry, suggested that changes in a gene called SKA2 plays a significant role in turning what might otherwise be an unremarkable reaction to the strain of everyday life into suicidal thoughts and behaviors.

"Suicide is a major preventable public health problem, but we have been stymied in our prevention efforts because we have no consistent way to predict those who are at increased risk of killing themselves," study leader Zachary Kaminsky, assistant professor at the Johns Hopkins University School of Medicine, said in a statement.

"With a test like ours, we may be able to stem suicide rates by identifying those people and intervening early enough to head off a catastrophe," Kaminsky said.

In a series of experiments involving brain samples from mentally ill and healthy people, Kaminsky and his colleagues found those who had killed themselves had significantly reduced levels of SKA2.

Further study found in some subjects a modification that altered the way the SKA2 gene functioned without changing the gene 's DNA sequence.

The modification added chemicals called methyl groups to the gene and higher levels of methylation were then found in the same study subjects who had killed themselves.