Serum SIRT-1 (9.36 ± 9.62 vs. 18.52 ± 14.90, p < 0.001), Nrf-2 (11.18 ± 10.53 vs. 22.05 ± 17.44, p < 0.001), and HO-1 (0.86 ± 0.95 vs. 1.89 ± 1.65, p < 0.001) levels were significantly lower in adults with ADHD compared to controls, whereas TNF-α levels did not differ between groups (7.49 ± 2.15 vs. 7.78 ± 2.06, p = 0.439). The gene discussed is TNF; the disease is attention deficit-hyperactivity disorder.