Researchers from Yale University believe they have homed in on a specific biomarker that can be linked to suicidal thoughts in subjects suffering from post-traumatic stress disorder (PTSD). The new study adds to a growing body of research into novel ways clinicians can identify patients at high risk of suicide.

The new research investigated levels of metabotropic glutamate receptor type 5 activity (mGluR5). Prior research has implicated excessive or abnormal mGluR5 activity in a variety of mood disorders, so the new study set out to investigate whether it could serve as a biomarker for suicidal ideation.

Using positron emission tomography (PET), the researchers quantified mGluR5 activity in two different cohorts, individuals with PTSD or individuals with major depressive disorder (MDD), as well as a third healthy control group. All subjects were also evaluated as to whether they currently had suicidal thoughts.

Interestingly, mGluR5 activity was distinctly up-regulated in PTSD subjects generally, compared to MDD subjects and the healthy control. But more importantly, those PTSD subjects suffering from current suicidal thoughts displayed higher mGluR5 activity than PTSD subjects without current suicidal ideations.

Oddly the study found no comparable increase in mGluR5 activity in MDD subjects with current suicidal thoughts. The researchers suggest this makes mGluR5 a highly specific biomarker signaling suicide risk primarily in subjects having experienced severe trauma resulting in PTSD.

Senior author on the study, Irina Esterlis, hopes this research could help clinicians better identify those patients needing urgent psychiatric interventions and even possibly lead to suicide prevention drugs that work by rapidly lowering mGluR5 activity.

"If you have people who suffer from high blood pressure, you want to reduce those levels right away," says Esterlis. "We don't have that option with PTSD."

The research adds to a compelling and growing body of work finding possible neurological biomarkers that can identify suicidal risk and ideation. Alongside a 2017 study finding brain inflammation can be linked to suicidal thoughts, a team of scientists created an algorithm that was able to examine a patient's brain scan and accurately predict whether that person suffered from suicidal tendencies.

Other researchers have identified a specific gene they claim that, when found in lower than average concentrations, can indicate a high propensity for suicide. This gene, known as SKA2, plays a role in how the brain handles stress hormones and it is suggested that detecting certain mutations in the gene through a blood test could indicate individuals more likely to commit suicide.

It is still early days for much of this work, and these intriguing brain biomarkers would need to be verified in larger cohorts before being rolled out into clinical environments. Still, finding a way to better identify those patients most in need of assistance could help prevent many sufferers from taking their lives.

The new research was published in the journal PNAS.

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