‘Could a blood test predict whether a person is at risk of committing suicide? For the first time, a set of proteins in the blood have been linked to suicidal behaviour. People who commit suicide appear to share a number of biological traits, regardless of any underlying conditions. This hints that suicidal behaviour may be a distinct disorder.

To investigate, Alexander Niculescu of Indiana University in Indianapolis and colleagues collected blood from the cadavers of nine men who had bipolar disorder and suicidal tendencies, and nine with bipolar but no suicidal thoughts, and compared levels of all the genes expressed in their blood.

Four genes were expressed at significantly higher levels in the blood of people who had been suicidal. Some proteins that these genes code for are known to be involved in stress and cell death.’ (New Scientist).