Characteristics of undiagnosed children with parent-reported ADHD behaviour.

There is an ongoing public debate on the diagnosis of attention deficit hyperactivity disorder (ADHD) in which critics have claimed that the disorder is over-diagnosed, while the potential under-diagnosis of children with ADHD has received little attention. In this study we estimate the number of children with parent-reported ADHD behaviour at age 7 and absence of recorded ADHD diagnosis through adolescence, and investigate whether socio-demographic characteristics of this group differed from the children diagnosed with ADHD during follow-up. Our study was based on data from the Danish National Birth Cohort, where parents of 51,527 children completed questionnaires, including the Strength and Difficulties Questionnaire (SDQ). ADHD diagnosis was identified through Danish registers and parent-reported ADHD behaviour by the specific SDQ subscale. Socio-demographic predictors of positive parent-reported SDQ ADHD behaviour and absence of recorded ADHD diagnosis in their children were examined using logistic regression analyses. Children with parent-reported ADHD behaviour and no diagnosis (1.3%) were more likely to be girls (OR 1.83; 95% CI 1.45; 2.29), more likely to have mothers with a low socioeconomic status (OR high vs. low 1.49; 95% CI 1.10; 2.02), and to live in certain regions of the country (OR: Capital vs. Southern: 2.04; 95% CI 1.51; 2.73) than children with an ADHD diagnosis. The children showed markedly impairments on all the SDQ subscales. The results demonstrate a considerable number of children with ADHD symptoms who potentially go undetected and underline the influence of socio-demographic factors in the pathway to a diagnosis of ADHD.