Protein-binding biomarker may indicate stress-related increase in suicidal ideation
Key takeaways:
- Presence of 11C-ER176 VT was associated with severity of suicidal ideation.
- There was no association with 11C-ER176 VT and suicide attempt history.
Presence of a protein-binding biomarker in a small cohort of adults with depression may be an indicator that suicidal ideation increases because of elevated stress, according to research from JAMA Psychiatry.
“The diathesis-stress model of suicide posits that suicide risk is multifactorial, reflecting complex interactions,” Sarah Herzog, PhD, an assistant professor of neurobiology at Columbia University Irving Medical Center, and colleagues wrote. “Elevated peripheral and central nervous system inflammation is one such potential neurobiological marker of a diathesis toward suicide risk.”
Brain translocator protein 18k Da (TSPO) binding, a biomarker indicative of neuroinflammation, is associated with stress and its presence is elevated in those with depression and suicidality; however, its impact on suicidality is unknown, Herzog and colleagues wrote.
They sought to examine the association of TSPO binding in patients with depression who experience daily acute stress-related suicidal ideation, as well as history of suicidal behavior and clinician-rated suicidal ideation.
From an initial cohort of 148 individuals who signed consent forms, the cross-sectional study included 53 adults (mean age, 29.5 years; 69.8% women) examined at the New York State Psychiatric Institute. All participants were diagnosed with major depressive disorder but free from schizophrenia spectrum disorders, active physical illness, cognitive impairment, substance intoxication or withdrawal at baseline.
Enrollees underwent positron emission tomography scans of TSPO binding with 11C-ER176 and concurrent arterial blood sampling, with the primary outcome the weighted average of 11C-ER176 total distribution volume (VT) as computed across 11 regions of the brain.
Following PET imaging, participants underwent psychiatric evaluation including the Beck Scale for Suicidal Ideation (BSS), Structured Clinical Interview for DSM-5 (SCID) and Columbia-Suicide Severity Rating Scale (C-SSRS), as well as self-reported depression severity via the Beck Depression Inventory.
Additionally, a subset of 21 participants completed 7 days of ecological momentary assessment (EMA). The protocol was initiated approximately 2 weeks from PET imaging, which included self-reportage of suicidal ideation, negative affect and environmental stressors up to six times per day.
According to the results, the presence of 11C-ER176 VT was associated with severity of suicidal ideation ( = 0.19; 95% CI, 0.03 to 0.39), with no differences regarding suicide attempt history ( = 0.18; 95% CI, 0.04 to 0.37).
Herzog and colleagues additionally reported that the presence of suicidal ideation, as measured by either BSS or EMA, was associated with higher 11C-ER176 VT ( = 0.21; 95% CI, 0.01-0.98); however, no association was found between suicide attempt history and TSPO binding, contrary to expectations, they wrote.
Among the subset of those who completed EMA, data showed that 11C-ER176 VT was associated with greater suicidal ideation and negative affect during EMA periods when stressors were present ( = 0.12; 95% CI, 0.01-0.23) compared with intervals where stress was not present ( = 0.19; 95% CI, 0.08-0.3).
“The current findings suggest that elevated TSPO binding is associated with the propensity to experience more severe depressive symptoms in the context of stress,” Herzog and colleagues wrote.