Vitamin D's Molecular Action Mechanism in Attention-deficit/Hyperactivity Disorder: A Review of Evidence

Background & Objective: Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous disorder characterized by hyperactivity, impulsivity and inattention. Children with ADHD have challenges with learning, behavior and psychosocial adjustments, sometimes retained into adulthood. The exact etiology of ADHD is unknown, and the pathophysiology of this disease is complex. Several hypotheses have been raised regarding ADHD pathogenesis, including serotonergic and catecholaminergic signalling pathway dysfunction, neurotropic-related factors, oxidative stress, or neuroinflammation. Vitamin D has an important protective effect against inflammation, oxidative stress and certain neurotrophic factors and neurotransmitter, as well as facilitating dopaminergic and serotonergic functions. Vitamin D levels in children with ADHD are lower than in healthy children, and thus may be involved in the pathogenesis of ADHD. These observations, therefore, confirm the neuroprotective role of vitamin D through multiple molecular mechanisms and can be considered as a promising target in understanding ADHD pathology. Conclusion: In this context, the present study reviews the molecular pathways of vitamin D in ADHD patients.