Serum Asprosin and Peptide Tyrosine Tyrosine (PYY) Levels in Bipolar Disorder

Objective: In our study, we aimed to investigate the differences in metabolic parameters, serum asprosin and peptide tyrosine tyrosine (PYY) levels in a bipolar disorder manic (BD-M) group, a euthymic group and in healthy controls; we also aimed to evaluate the relationship of asprosin and PYY levels with metabolic parameters and psychopathology in patients. Methods: The study included 54 manic patients, 40 euthymic patients and 39 healthy controls. The sociodemographic characteristics of the participants were recorded, and biochemical parameters and asprosin and PYY levels were measured. The Young Mania Rating Scale (YMRS) and the Hamilton Depression Rating Scale (HAM-D) were completed. Results: Body mass index (BMI) showed significant differences between the three groups (p < 0.001); the lowest was found in the control group and the highest in the euthymic group. Triglyceride levels were significantly higher in the euthymic group compared with the BD-M group and controls (p = 0.003). Glucose levels were significantly higher in the BD-M group compared with euthymic (p_{manic-euthymic} = 0.008) and controls (p_{manic-control} < 0.001). Asprosin (p_{manic-control} < 0.001, p_{euthymic-control} = 0.046, p_{manic-euthymic} = 0.015) and PYY (p_{manic-control} < 0.001, p_{euthymic-control} = 0.037, p_{manic-euthymic} = 0.002) levels were significantly different between the three groups, with the lowest levels in the BD-M group and the highest levels in the control group. The eta squared = 0.18 for asprosin and 0.21 for PYY. In the BD-M group, a moderate negative correlation was found between YMRS and asprosin (r = -0.345; p = 0.011) and PYY (r = -0.376; p = 0.005) levels. ROC analysis results showed that asprosin and PYY could be used to predict the manic period in BD-I (AUC_asprosin:0.775; AUC_PYY:0.760). After adjusting for asprosin as a covariate using ANCOVA, the difference in PYY between groups remained significant (manic-euthymic groups, p = 0.040; manic-control groups, p = 0.013). Conclusions: The study results revealed that asprosin and PYY levels were low, and metabolic parameters were impaired in the patients. Low asprosin and PYY levels may be indicators of impaired energy homeostasis in BD-I. PYY may be a state marker for manic episodes.