Co-Development of ADHD and ODD Symptoms from Toddler to Preschool Years: A Parallel Process Model

We examine how ADHD and ODD symptoms change together and predict one another in early childhood. Findings suggest that these disorders co-develop starting as young as age 2. ADHD symptoms at age 2 conferred risk for increasing ODD symptoms. Early interventions targeting ADHD symptoms might reduce the risk of comorbidities.