By Alan Mozes
Now, a small, new study suggests it's possible simply by tracking the way a common brain chemical is distributed across the brain.
The investigation involved fewer than 90 patients. But it nevertheless raises the possibility that at some future point new treatments could be developed to reduce suicide risk in this vulnerable group of patients.
"Individuals with mental disorders are at higher risk for suicidal thinking and actions, and currently there is not a treatment to relieve suicidal thinking in PTSD [post-traumatic stress disorder]," noted study author Irina Esterlis. She is an associate professor of psychiatry at Yale University School of Medicine in West Haven, Conn.
"In fact, there are only two U.S. Food and Drug Administration-approved treatments for PTSD," said Esterlis. Both are antidepressants known as SSRIs (selective serotonin reuptake inhibitors). But they "do not work fast, and may not work well in about half of individuals," she noted.
The new work points to a telltale type of brain activity that may unleash classic PTSD symptoms, such as the desire to avoid people or places associated with a traumatic event and/or feelings of tension.
Among those with PTSD, such symptoms can trigger suicidal thinking, Esterlis explained.
"Thus, it would be important to understand when the alteration in this [brain activity] happens, so we can 'fix' it at an optimal time," said Esterlis, who also works at the U.S. Department of Veterans Affairs' National Center for PTSD.
The brain chemical in question is a so-called "glutamate receptor" known as mGlurR5.
Found throughout all regions of the brain, it plays a role in regulating learning, memory and sleep, experts say. Animal studies have also linked changing mGlurR5 patterns to anxiety and depression risk.
With that in mind, investigators used PET scans to monitor how these receptors behaved across five different brain regions among 29 PTSD patients, 29 patients diagnosed with major depressive disorder, and 29 healthy patients.
In the end, scans taken of PTSD patients while they had thoughts of suicide showed that at such moments these receptors tended to gather outside of brain cells, as opposed to inside brain cells.
"We found that there was about 30% more of these receptors on the outside of the cell in individuals with PTSD who had suicidal thinking, as compared to mentally healthy individuals," noted Esterlis.
This outside-leaning pattern made the receptors more actively "available." And such availability was found to be significantly higher across all five scanned brain regions in PTSD patients compared with healthy controls, and across three regions compared with depressed patients.
Esterlis reiterated that "a lot more work will be happening" to further investigate such differences, and whether such patterns might ultimately serve as risk screening tools or therapy targets down the road.
The findings were published May 13 in the of Proceedings of the National Academy of Sciences.
Dr. Jeffrey Borenstein, president of the Brain & Behavior Research Foundation in New York City, said the findings are a positive step forward.
"Obviously more work needs to be done," he said. "But to me, it's very hopeful when scientists are able to find and develop a better understanding of how the brain works and what's going on when people experience certain conditions." He was not involved with the study.
"So, this is a preliminary finding," Borenstein stressed. "But it has the potential for leading to the type of useful biomarker that can help with both diagnosis and treatment decisions for patients with conditions such as PTSD. We do have treatments. But we need better treatments. It's extremely important. And this could turn out to be helpful."