Levels of serum galectin-1, galectin-9 and YKL-40 in bipolar disorder and their relationship with cognitive functions

Bipolar disorder is a common chronic mental illness that causes significant morbidity and mortality in the society. In recent years, there has been an increasing interest in studies on the role played by neuroinflammation in the etiopathogenesis of bipolar disorder. In this study, we investigated the role of galectin-1, galectin-9 and YKL-40, which are thought to have a role in neuroinflammation, in the etiopathogenesis of bipolar disorder and the relationship of these parameters with cognitive functions. According to our best knowledge, there is no study in the literature investigating the relationship between bipolar disorder and galectin-1, galectin-9 levels, and there are very few studies investigating the relationship of this disease with YKL-40. Our study was planned as a prospective paired case-control study. 64 patients in the euthymic period who were diagnosed with bipolar disorder according to DSM-5 diagnostic criteria or followed up with this diagnosis, who applied to Gaziantep University Mental Health and Diseases Clinic between June 2021 and February 2022, without any additional diagnosis, were included in the study. 64 healthy controls without any disease, matched according to gender, age, smoking and educational status, were also included in the study. Young Mania Rating Scale (YMRS) and Hamilton Depression Rating Scales (HDRS) were administered to all participants in the study. Clinical interviews were made with the patients, cognitive tests were applied, and then blood tests were applied to determine the levels of the parameters (galectin-1, galectin- 9, YKL-40) that we think are related to neuroinflammation. Stroop test and trail making test were performed to evaluate cognitive functions. In our study, serum galectin-1, galectin-9 and YKL-40 levels were statistically significantly lower in the patient group compared to the healthy control group. Stroop test and trail making test scores for evaluating cognitive performance were statistically higher in the patient group than in the healthy control group. There was a weak positive correlation between serum galectin-1, galectin-9 and YKL-40 levels and cognitive performance in all participants. In our study, galectin-1, galectin-9 and YKL-40 serum levels were significantly lower in the patient group, suggesting an important role of these parameters in neuroinflammation. The fact that the Stroop and trail making test scores of the patient group were statistically higher than the control group indicates that the cognitive performance of the patient group was weaker. In addition, the weak positive correlation of galectin-1, galectin-9 and YKL-40 levels with cognitive performance also points to the neuroprotective role of these molecules. We believe that this study will contribute to this field where there is very limited data in the literature.