Table 3.
Differences in the metabolites of the kynurenine and serotonin pathways
| MDD without T2DM |
MDD with T2DM |
p-value | Adjusted p-value |
Effect size | |
|---|---|---|---|---|---|
| Kynurenine pathway Metabolites | |||||
| Tryptophan | 0.205 [0.167–0.238] | 0.193 [0.164–0.204] | 0.36 | 0.15 | 0.15 |
| N-formylkynurenine | 3.314 × 10−5 [2.830 × 10−5–3.913 × 10−5] | 3.018 × 10−5 [2.342 × 10−5–4.092 × 10−5] | 0.69 | 0.39 | 0.07 |
| Kynurenine | 6.413 × 10−3 [4.758 × 10−3–7.710 × 10−3] | 6.832 × 10−3 [4.966 × 10−3–7.794 × 10−3] | 0.40 | 0.59 | 0.14 |
| Kynurenic acid | N.D | N.D | – | – | – |
| 3-Hydroxykynurenine | 6.670 × 10−5 [5.740 × 10−5–8.336 × 10−5] | 7.353 × 10−5 [4.978 × 10−5–11.16 × 10−5] | 0.62 | 0.81 | 0.08 |
| 3-Hydroxyanthranilic acid | N.D | N.D | – | – | – |
| Quinolinic acid | 9.588 × 10−5 [6.642 × 10−5–1.368 × 10−4] | 1.372 × 10−4 [1.033 × 10−4–1.978 × 10−4] | 0.045 | 0.36 | 0.32 |
| Picolinic acid | N.D | N.D | – | – | – |
| Xanthurenic acid | N.D | N.D | – | – | – |
| Serotonin pathway Metabolites | |||||
| Pretonine | 5.012 × 10−5 [4.045 × 10−5–5.293 × 10−5] | 4.633 × 10−5 [4.241 × 10−5–5.965 × 10−5] | 0.89 | 0.63 | 0.02 |
| Serotonin | 6.565 × 10−5 [3.350 × 10−5–2.758 × 10−4] | 1.233 × 10−4 [4.593 × 10−5–2.756 × 10−4] | 0.51 | 0.61 | 0.11 |
| N-Methylserotonin | N.D | N.D | – | – | – |
P-values are adjusted for age, sex, and BMI. The p-value was calculated using the Mann–Whitney U test, and the adjusted p-value was determined by multiple regression analysis. Effect sizes were calculated using the Mann–Whitney U test. BMI body mass index, N.D. not detected, MDD major depressive disorder, T2DM type 2 diabetes mellitus