Predictors of preschool attention-deficit/hyperactivity disorder diagnosis: a population-based study using national registers

This Swedish population-based study of 631,695 children identified 39 of 41 examined predictors associated with increased risk of ADHD diagnosis before age 6, including psychiatric comorbidities, medical conditions, parental history, and perinatal factors. Novel associations were found with gastroesophageal reflux disease, premature contractions during pregnancy, and parental criminal conviction history.