Correlations between neutrophil/lymphocyte, platelet/lymphocyte, and monocyte/lymphocyte ratios (NLR, PLR, and MLR, respectively) and psychopathological and clinical variables in the context of mood disorders are increasingly emerging in international scientific literature, being the former one of the most studied. The estimation of suicidal risk associated to affective disorders could benefit from such rapidly and easily available biomarker of inflammation, if significant in this regard.

The present review would like to focus on any existing correlations between NLR and suicidal risk in patients with mood disorders.

We sourced articles on the topic found in major scientific literature databases, combining the keywords “neutrophil/lymphocyte ratio”, “NLR”, “mood disorders”, “major depressive disorder”, “bipolar disorder” and “suicide risk”.

There are congruent findings of significantly higher NLR values in depressed patients attempting suicide than in depressed patients with no suicidal behaviors or healthy controls. In addition, violent means appear typical in this subgroup of depressed suicidal patients, suggesting that patients with higher levels of NLR are at risk of attempting suicide and to be successful in self-harming. Similar results have been found in patients with bipolar disorder, showing a positive correlation between NRL and suicide risk, evaluated by the Suicide Behaviors Questionnaire-Revised (SBQ-R). Moreover, in patients with a positive family history for suicide attempts, NRL was found to be a significant positive predictor of suicide risk.

These findings, although limited, support the notion that NLR might be a useful marker for suicide vulnerability in both BD and MDD patients.

No significant relationships.

Suicidality is one of the most common complications of mental disorders, so that the identification of potential biomarkers may be relevant in clinical practice. To date, the role of serum lipids and neutrophil/lymphocyte ratio (NLR) has been explored albeit with conflicting results. To the best of our knowledge, no study has explored lipid levels concomitantly with NLR in relation to violent suicide attempts. Therefore, we aimed to investigate whether serum lipid levels and NLR might be associated with the violent method of suicide attempts.

The study group consisted of 163 inpatients who attempted suicide. Blood samples were collected at the beginning of hospitalization to measure total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein, very-low-density lipoprotein (VLDL), triglycerides, and NLR. Descriptive analyses of the total sample were performed. The included patients were divided into two groups according to violent/nonviolent method. Groups were compared in terms of lipid (MANCOVAs).

Plasma levels of total cholesterol (F = 5.66; P = .02), LDL (F = 4.94; P = .03), VLDL (F = 5.66; P = .02), and NLR (F = 8.17; P < .01) resulted to be significantly lower in patients that used a violent method compared to patients who attempted suicide with a nonviolent method.

Low cholesterol, LDL, and VLDL levels as well as low NLR value were associated with a violent method of suicide attempt in patients with mental disorders. Further studies are needed to confirm these results.