According to the World Health Organization, over 800,000 people take their own lives each year. And for every suicide, there are many more who make attempts. In fact, a suicide attempt is made every minute of every day.
If we could better predict who was at risk for suicide, then we could more effectively intervene to reduce this tragic burden on individuals, families, and public health.
Now, a new analysis of existing studies has revealed a link between inflammation and suicide.
Inflammation is part of a complex biological response to damaging stimuli, including injuries, pathogens, and irritants. It sparks your immune system into action in an attempt to protect you from harm. Most of the time, inflammation is a good thing, as it serves as a protective mechanism.
But chronic inflammation can lead to serious health issues.
This new analysis strongly supports the idea that there are increased levels of chemicals, called cytokines, in the body and brain that promote inflammation in individuals who are contemplating or have attempted suicide, even when compared to patients being treated for the same psychiatric disorders who are not suicidal.
These cytokines are known to be involved in problems in other parts of the body, such as the joints (arthritis), the coronary arteries (atherosclerosis), and the lungs (asthma). Studies have long suggested that cytokines are released under conditions of psychological stress and that inflammation in the brain contributes to depression. The current study suggests that suicide emerges in the context of a relatively greater activation of the immune system than typical stress or depression.
To conduct this research, Drs. Carmen Black and Brian Miller at Georgia Regents University collected and pooled data from 18 published studies, resulting in a combined total of 583 psychiatric patients with suicidality, 315 psychiatric patients without suicidality and 845 healthy control subjects. Their analysis revealed that patients with suicidality had significantly increased interleukin (IL)-1β and IL-6 levels in blood and postmortem brain.
Dr. Miller explained:
Our findings contribute to a growing body of evidence that immune system dysfunction, including inflammation, may be involved in the pathophysiology of major psychiatric disorders in some individuals. Specifically, cytokine levels may help distinguish patients with suicidality from patients without suicidality and controls. That levels of IL-1β and IL-6 were altered in both blood and postmortem brain supports the robustness of our findings, as changes in the periphery might not be mirrored in the central nervous system.
The study did have a limitation: the relationship between elevated cytokine levels and suicide may be non-specific, meaning that increased levels may not determine whether a specific person is going to attempt suicide at a specific time.
A specific suicide test is still a distant goal. However, by identifying biological markers generally associated with suicide, researchers say they may be getting closer to creating simple blood tests that would help doctors predict long-term risk, similar to how increased blood pressure may predict medical problems years or decades later.
Studies are still needed to evaluate whether controlling inflammation earlier in life has a long-term protective effect. And, rigorously designed studies of large and diverse patient samples are still needed to confirm the presence of these cytokine alterations, but if replicated, such findings could contribute to more personalized medicine for patients.
Dr. John Krystal, Editor of Biological Psychiatry, said of the findings:
Inflammation affects every organ in the body. It is increasingly evident that we need to take a long-term perspective on the effects of inflammation on the brain. The path to preventing suicide may be to intervene early in long-term processes that increase the risk for suicide rather than to focus solely on the elusive short-term predictors of suicide.
Dr. Miller agreed:
Given that suicide is a major area of public health concern, it is critical to investigate potential markers of suicidality that could be used to assess treatment effectiveness, advance suicide prevention efforts and even help pave the way for future immune-based therapeutic interventions.