Plasma Orexin A and mRNA Expression Levels of Pre-pro-orexin Gene in Attention-Deficit Hyperactivity Disorder

Background: Attention deficit hyperactivity disorder (ADHD) is an early onset, highly heritable, clinically heterogeneous, long-term impairing disorder with tremendous impact on individuals, families, and societies. It affects 7.5% of school-aged children in Taiwan. Emerging evidence has suggested that patients with ADHD may present with a deficit of attention, alertness and sleep disturbances. Since attention, alertness, and sleep disturbances may significantly increase the functional impairment of ADHD, gaining insight into their pathophysiology as well as into their treatment is of relevance to provide a better clinical management of patients suffering from ADHD. The orexin system, located in the hypothalamus, takes an important role in homeostatic functions, such as attention, alertness, sleep-wake cycle, and feeding. To our best knowledge, the functioning of the orexin system has never been investigated in patients with ADHD. Given the involvement of the orexin system in the control of alertness and reward seeking, the present study aims to examine whether plasma orexin and mRNA expression levels of pre-pro-orexin gene are associated with the symptoms and neurocognitive deficits of ADHD.