Serum Kynurenine Levels in Patients of Depression with and without Suicidality: A Case-control Study

Abstract

Introduction: Depression is a common mental health disorder and suicide is one of the most dreaded outcomes of depression. In India, the suicide rate is reported to be 12.91 of 100,000 population and as per the estimates, it is further going to increase in time to come. Several potential biomarkers for suicidality have been identified over the last years in an effort to devise an investigational test to detect suicidality. Kynurenine, a tryptophan metabolite, is one of the potential biomarkers as it has been found to be elevated in patients with suicidality. Aim: To assess the levels of kynurenine in patients of severe depression with and without suicidal attempt. Materials and Methods: This was a case-control study conducted in MGM Medical college, Indore from April 2020 to March 2021. Socio-demographic parameters like age, gender, residence, marital status were collected along with hamilton depression rating score, suicidal behaviour questionnaire score. Blood samples of sixty patients with depression having suicide attempt (case group) were compared to the similar parameters of the 60 patients with depression not having any history of the suicide attempt (control group). Data obtained was analyzed using Statistical Package for Social Sciences (SPSS) version 23.0 and relevant statistical tests were applied with the p-value <0.05 was considered as statistically significant. Results: Mean age of the case group was 39.03±11.58 years and in control group was 41.92±11.62 years. The mean serum kynurenine for depression with suicidal attempt was 464.05±89.11 ng/mL which is considered a high value as per the criteria for cut-off for normal level.While for depression without suicidal attempt was 420.78±69.66 ng/mL which is low. The present study had a positive correlation of serum kynurenine levels with the suicidal behaviour questionnaire (r-value=0.48, p-value=0.001) but not with the hamilton depression rating scale (r-value=-0.243, p-value=0.061). Conclusion: Case group has shown higher mean serum kynurenine than control group, which was statistically significant. This study concluded that, serum kynurenine was not correlated with the severity of depression which makes it a good prospective for further research as a biomarker for early prediction of suicidality.