Six biomarkers stood out as significant indicators

Across the world, one million people commit suicide every year. Now, a simple blood test that looks for enhanced expression of a few genes can quite accurately identify people who are at great risk of committing suicide.

Since people planning to commit suicide do not always share their intentions with others, a reliable tool that can “assess and track changes in suicide risk” would go a long way in preventing such deaths.

A team led by Prof. Alexander Niculescu from Indiana University School of Medicine, Indianapolis has found that enhanced expression of four genes can indicate a person’s inclination to commit suicide. Their study was recently published in the Molecular Psychiatry journal.

Seventy-five bipolar individuals were studied to find the genomic biomarkers using blood samples. Prior to drawing blood samples at three to six months interval, the subjects completed a questionnaire wherein they revealed their state of mind — suicidal ideation.

Of the 75 people studied, suicidal ideation (SI) of nine subjects changed from zero to a high score of two and above in the Hamilton Scale for Depression. The Hamilton Scale has a range from zero to four.

The gene expression in the nine people was compared when they had no suicidal thoughts and when it shot up to a high-risk state. This helped in identifying the candidate biomarkers.

To narrow down the number of candidate biomarkers, and to validate the results, the gene expression results from the bipolar group were compared with those of nine males who had committed suicide. “These [nine] people were from the general population, not psychiatric patients per se,” noted Prof. Niculescu in an email to this Correspondent.

Six biomarkers stood out as significant indicators of suicidal ideation. By comparing the results with their previous work, the authors found that genetic association evidence of suicidal risk was particularly present in the case of four of the six genes.

In the case of bipolar subjects, the suicidal tendency may be associated with dysphoric mood (a general feeling of unhappiness), increased psychosis, anxiety and stress. Two biomarkers in particular serve as “key state and trait factors” in those with psychotic mood disorders.

Finally, the results were compared with subsequent and previous hospitalisations from attempted suicide by 42 men with bipolar and 46 with schizophrenia. The four genes were found to serve not only as state markers (immediate risk) but also as trait markers (future risk) in those with bipolar disorder.

“To our surprise, the expression of these genes correlates with future (as well as past) hospitalisations from suicidality,” Prof. Niculescu noted.

Accuracy

The accuracy in identifying suicidal ideation shot from 65 per cent to 83 per cent when the expression of one biomarker (SAT1) was compared with clinical symptoms like anxiety, mood and psychosis in those who were hospitalised following attempts to commit suicide. The accuracy was 79 per cent in those who had SAT1 and one clinical symptom (anxiety). “We do not yet know how these findings apply to other high risk groups, such as those with major depressive disorders,” he said.

But there are several unknown areas. For instance, suicidal thoughts and feeling may be very different from suicidal actions. This would mean that just the thought of committing suicide need not always translate into action. The present study did not address this.