Suicide is a worldwide public health concern. However, there were no objective biomarkers of suicide risk, and self-reported data might be incorrect, limiting prediction, diagnostic, and therapy efforts. Patients, researchers, and doctors would benefit greatly from reliable biomarkers that can discriminate between diagnostic subgroups, forecast deteriorating symptoms, or identify novel therapeutic targets.

Using the search keywords (suicide*) AND (biomarker*) OR (indicate*), MEDLINE was searched for studies published between 2016 and 2021. Investigators considered studies that evaluated biomarkers between suicidal ideation, suicide attempt, suicide death, or any suicide subgroup to other neuropsychiatric illnesses. To confirm that biomarkers were specific to suicide and not other disorders, studies comparing suicidal behavior or suicide death with healthy controls were excluded.

The study highlighted the previous 5 years of research on suicide-associated biomarkers and gave a complete reference for promising and innovative biomarkers that encompass different presentations of suicidal thought, suicide attempt, and suicide death. Serotonin, inflammation, the hypothalamic-pituitary-adrenal axis, lipids, and endocannabinoids emerged as the most promising diagnostic, prognostic, and therapeutic markers.

The importance of diagnostic and predictive biomarkers, especially in suicide prevention, cannot be overstated. While larger-scale studies and more in-depth studies were needed, the previous 5 years of research found critical biomarkers that might ultimately enhance prediction techniques, aid diagnostics, and aid in the development of future treatment targets.