Vitamins B₉ and B₁₂ in children with attention deficit hyperactivity disorder (ADHD)

Background: Attention deficit hyperactivity disorder (ADHD) is a common childhood neurodevelopmental disorder that begins before age 12. Given the role of B group vitamins in cell metabolism, synthesis of nucleotides, and neurotransmitters, the present study systematically investigated the plasma levels of vitamins B₉ and B₁₂ in children with ADHD. Methods: We searched electronic databases including Web of Science, MEDLINE, EMBASE, Scopus, Iran MEDEX, Cochran database, and SID from conception to June 2023. Full-text case-control or cross-sectional studies were included in this study. Participants in the case group were children with ADHD aged 6-12 years. Review Manager Software (RevMan 5.4) was used for statistical analyses. Standardized mean differences (SMD) with 95% CIs were used to determine the differences between the two groups. Results: Six studies were included in the present meta-analysis. They included 982 children, of whom, 204 were girls and 744 were boys. The mean age of the children was 8.86±2.03 years. The level of vitamin B₉ was significantly different between children with and without ADHD [SMD -0.80, 95% CI (-1.55, -0.04)]. Vitamin B₁₂ was significantly lower in children with ADHD [SMD -0.29, 95% CI (-0.42, -0.16)]. However, due to high heterogeneity (I² = 93%), sensitivity analysis was used, I² fell to 21%, and significant difference was observed between the two groups [SMD -0.19, 95% CI (-0.34, -0.04)]. Conclusion: The results of this systematic review showed that the level of vitamins B₉ and B₁₂ in children with ADHD was significantly lower than that in healthy children.