Psychosocial Burden of Undiagnosed Persistent ADHD Symptoms in 12-Year-Old Children: A Population-Based Birth Cohort Study.

To describe the psychosocial functioning in children with undiagnosed persistent ADHD symptoms. A prospective, population-based birth cohort study was conducted among 2,945 children and their primary caregivers who lived in Tokyo, Japan, and were followed up at the age of 10 years and 12 years. Parents reported a history of ADHD diagnosis and completed the Strengths and Difficulties Questionnaire. Overall, 91 participants had persistent ADHD symptoms; however, 76 (83.5%) had no history of an ADHD diagnosis. The presence of undiagnosed ADHD symptoms was significantly associated with worse psychosocial functioning for most continuous outcomes when compared with the absence of ADHD symptoms and diagnosis, including lower self-esteem (standardized mean difference [SMD] = -0.31) and higher depression (SMD = 0.36), emotional symptoms (SMD = 0.69), conduct problems (SMD = 1.26), and peer relationship problems (SMD = 0.98). Our findings suggest the importance of paying more attention to the possible underdiagnosis of ADHD in children.