Vitamin D deficiency in adolescents is significantly associated with both attention-deficit/hyperactivity disorder (ADHD) and depression prevalence, according to study results presented at the American Academy of Child and Adolescent Psychiatry (AACAP) 2023 Annual Meeting, held from October 23 to 28, 2023 in New York, New York. However, the relationship between vitamin D and ADHD only becomes marginally significant when accounting for depression.