HMOX1 and attention deficit-hyperactivity disorder: To evaluate serum tumor necrosis factor-alpha (TNF-α), heme oxygenase-1 (HO-1), nuclear factor erythroid 2–related factor 2 (Nrf-2), and sirtuin-1 (SIRT-1) levels in adults with ADHD and to examine their associations with symptom severity and clinical features.