Medical disorders in a Danish cohort of children with attention-deficit hyperactivity disorder.

Studies have identified a higher prevalence of co-existing psychiatric and medical disorders in children with ADHD. There is a shortage of longitudinal studies providing an overview of potential medical disorders in children with ADHD. The objective of this study was to provide a broad overview of lifetime prevalence and relative risk of medical disorders in a nationwide Danish cohort of children with and without ADHD during the first 12 years of life. A population-based prospective follow-back cohort study used data from Danish national health registries to identify a cohort of all children born in Denmark between 1995 and 2002. The children were followed from birth until 12 years of age in two national registries. Children with ADHD had a significantly higher prevalence of recorded diagnoses across all included chapters of medical disorders in the ICD-10, except for neoplasms, where the association with ADHD was non-significant. The highest relative risk was observed for the chapter concerning diseases of the nervous system, with episodic and paroxysmal disorders being the most frequently registered underlying category. The findings indicate that children with ADHD have an increased risk of a broad range of medical disorders compared to the general population during the first 12 years of life, except for neoplasms.