The Effect of Vitamin D3 Supplementation on Serum BDNF, Dopamine, and Serotonin in Children with Attention-Deficit/Hyperactivity Disorder

Background & Objective: Attention-Deficit/Hyperactivity Disorder (ADHD) is one of the most common psychiatric disorders in childhood. The exact etiology of this disease is unknown, but it is believed to be related to the disorder of catecholaminergic and serotonergic systems. Also, serum vitamin D levels in patients with ADHD is lower. Several studies have also shown the effect of vitamin D on the synthesis pathways of dopamine, serotonin, and a number of neurotrophic factors. Therefore, this study aimed to investigate the effect of vitamin D3 supplementation on serum levels of Brain-Derived Neurotrophic Factor (BDNF), dopamine, and serotonin in school-aged children with ADHD. Methods: Eighty-six children with ADHD were divided into two groups, based on randomized permuted blocks. Patients received 2000 IU vitamin D/day or a placebo for 12 weeks. Serum levels of BDNF, dopamine, serotonin, and 25-hydroxyvitamin D [25(OH)D] were measured at baseline and at the end of the study. Results: Serum levels of 25(OH)D and dopamine significantly increased in the vitamin D group, compared to the placebo group (p < 0.05). However, serum BDNF and serotonin levels did not change significantly. Conclusion: Vitamin D3 supplementation in children with ADHD can increase serum dopamine levels, but further studies are needed to determine the effects of vitamin D on neurotrophic factors and serotonin.