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Table 1 Clinical and biochemical data

From: Serum concentrations of kynurenines in adult patients with attention-deficit hyperactivity disorder (ADHD): a case–control study

  ADHD N Control N p value
133 131
Female, N (%) 71 (53.4) 133 75 (57.3) 131 0.52a
Age (range 18–40), median (SD) 28.0 (6.5) 133 22.5 (2.8) 131 <0.001***b
Alcohol problems, N (%) 24 (19.2) 125 1 (0.8) 131 <0.001***a
Problems with illicit drugs, N (%) 34 (27.0) 126 0 (0.0) 131 <0.001***a
Serious anxiety and/or depression, N (%) 82 (65.1) 126 5 (3.8) 126 <0.001***a
Bipolar disorder, N (%) 12 (9.9) 121 0 (0.0) 131 <0.001***a
Moderate smokersd, N (%) 51 (38.3) 133 12 (9.2) 131 <0.001***a
Heavy smokersd, N (%) 27 (27.8) 133 4 (3.1) 131 <0.001***a
Total WURS (range 0–100), median (SD) 60.0 (16.9) 118 12.0 (10.4) 129 <0.001***b
Total ASRS (range 0–72), median (SD) 47.0 (11.6) 123 22.0 (7.7) 128 <0.001***b
Combined typee, N (%) 65 (52.8) 123 3 (2.3) 128 <0.001***a
Hyperactive typee, N (%) 3 (2.4) 123 1 (0.8) 128 0.32a
Inattentive typee, N (%) 31 (25.2) 123 4 (3.1) 128 <0.001***a
Tryptophanf, i 77.3 (68.1–92.3) 133 83.6 (76.6–94.0) 130 0.004**c
Kynureninef, i 1.51 (1.29–1.78) 133 1.57 (1.40–1.76) 130 0.15c
Kynurenine/tryptophan ratio (KTR)g, i 19.0 (16.5–21.6) 133 18.4 (16.7–20.8) 130 0.46c
3-hydroxykynurenine (HK)h, i 31.8 (22.2–39.4) 131 30.6 (26.1–28.1) 130 0.43c
Kynurenic acid (KA)h, i 38.9 (30.9–52.2) 131 46.7 (34.0–57.5) 130 0.03*c
Xanthurenic acid (XA)h, i 14.2 (11.0–22.4) 131 18.9 (13.7–24.7) 130 0.004**c
Anthranilic acid (AA)h, i 19.4 (13.2–24.3) 131 17.6 (14.9–22.8) 130 0.52c
3-hydroxyanthranilic acid (HAA)h, i 29.8 (20.0–40.1) 131 35.4 (29.2–46.5) 130 <0.001***c
Quinolinic acid (QA)h, i 303 (258–387) 131 306 (274–364)  130 0.76c
Riboflavin (Vit. B2)h, i 18.1 (12.7–25.9) 131 19.9 (16.1–28.3) 130 0.02*c
Total vitamin B6h, i 58.5 (41.8–83.9) 131 67.1 (49.0–88.4) 130 0.05*c
Cotinineh, i 678 (2.48–1088) 131 1.2 (0.55–6.06) 130 <0.001***c
  1. Significance <0.001: ‘***’, <0.01: ‘**’, <0.05: ‘*’
  2. aχ2 test
  3. bStudent’s T test
  4. cMann–Whitney U test
  5. dCalculated based on serum cotinine levels: 80–1000 nmol/l: moderate smoker, >1000 nmol/l: heavy smoker
  6. eCalculated based on ASRS scores: A score of 21 or higher on the nine questions on inattentiveness is indicative of inattentive type, while a score of 21 or higher on the hyperactivity/impulsive questions is indicative for hyperactive/impulsive type. Combined type requires a score of 21 or higher on both subscales
  7. fμmol/L
  8. gμmol/μmol
  9. h nmol/L
  10. iMedian (25–75 percentile)