Researchers measured three brain chemicals—phoenixin, spexin, and kisspein-10—in the blood of teens with bipolar disorder and compared them to healthy peers. They found lower phoenixin and higher spexin in the bipolar group, but kisspein-10 levels were about the same and not statistically different.

The aim of the study was to assess concentrations of the following neuropeptides: phoenixin, spexin and kisspeptin in venous blood serum of children and adolescents suffering from bipolar disorder, and by this their predictive efficiency in this disorder. The study covered 75 individuals with a mean age of 15.26 years (95% CI: 14.86-15.67), of which the study group comprised of 57 individuals diagnosed with bipolar affective disorder and the control group - 18 individuals with no psychiatric diagnosis and no pharmacological treatment. Phoenixin, spexin and kisspeptin levels were determined in the peripheral venous blood serum. Neuropeptide concentrations were measured with the enzyme-linked immunosorbent assay (ELISA). The mean phoenixin concentration in the studied group equalled 1.57 ng/ml (95% CI: 1.35-1.79), while in the control group - 2.69 ng/ml (95% CI: 2.38-3; U Mann-Whitney test p-value < 0.05). For spexin, these results were 639.65 pg/ml (95% CI: 558.86-720.44) in the studied group, and 354.28 pg/ml (95% CI: 310.33-398.22; U Mann-Whitney test p-value < 0.05) in the control group. The observed differences were statistically significant. The mean concentration of kisspeptin levels in the studied group was 126.02 pg/ml (95% CI: 39.82-212.23; median: 59.85), while in the control group - 54.83 pg/ml (95% CI: 39.23-70.43; median: 51.3; U Mann-Whitney test p-value = 0.29), and the observed difference was not statistically significant. The occurrence of bipolar disorder symptoms is statistically significantly linked with a decreased phoenixin concentration and to a small degree - with an increased spexin concentration in blood serum of patients. However, it is not linked with the kisspeptin concentration.