الفهرس 
ATTENTION DEFICIT HYPERACTIVITY DISORDEROnly 14 pages are availabe for public view
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Abstract
Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorders in childhood and adolescence, affecting 2.2 to 17.8% of all school-aged children and adolescents.
ADHD in children has been associated with a wide range of developmental deficits including limitations of learning or control of executive functions as well as global impairments of social skills. The Diagnostic Statistical Manual of fifth revision, DSM-5, defines ADHD as a neurodevelopmental disorder characterized by impairing levels of inattention, disorganization, and/or hyperactivity– impulsivity. Inattention and disorganization involve failure to stay on task, seeming not to listen, and losing materials, at levels that are not consistent with age or developmental level. Hyperactivity– impulsivity entails overactivity, fidgeting, inability to stay seated, intruding into other people’s activities, and inability to wait. In childhood, ADHD frequently overlaps with other mental disorders including oppositional defiant disorder and conduct disorder.
The causes of ADHD are not fully understood; however, several environmental (e.g., exposure to certain foods or inhalants) and genetic risk factors have been proposed. It has been suggested that dietary interventions such as ω-3 FA and vitamin and mineral supplementation might affect ADHD symptoms.
Recently a number of studies have proposed that vitamin D might play a role in ADHD pathogenesis. The mechanisms by which vitamin D might affect a number of neurological diseases, including ADHD, are not clear. Nevertheless, there is evidence demonstrating the widespread presence of vitamin D receptors and 1α-hydroxylase (the enzyme responsible for the formation of the active vitamin) in the human brain; therefore, it is suggested that vitamin D might have neurohormonal properties in the human brain. Furthermore, a recent study proposed that vitamin D directly upregulates expression of tyrosine hydroxylase (a ratelimiting enzyme in dopamine synthesis) by binding to the nuclear vitamin D receptor. It is also suggested that this vitamin is involved in the synthesis of serotonin in the brain.