According to a study of 1331 ADHD patients and the same number of controls aged under 18, only 8.15% of ADHD patients had normal serum vit D levels (24). In another study, the prevalence of vit D deficiency in patients with ADHD over the age of 16 has been reported to be 27% in New Zealand (25). This evidence concerns the gene VIT and attention deficit-hyperactivity disorder.