This study aimed to examine which sociodemographic, clinical and psychological identifiers can determine which children with high hyperactivity/inattention symptoms are diagnosed with ADHD and those who are not. It also investigates whether receiving a diagnosis of ADHD is associated with better or worse socio-emotional measures for children with ADHD symptoms.
This study used data from an ongoing national study of Irish children (Growing Up in Ireland – the National Longitudinal Study of Children), which collected information on children’s physical, psychological and social development. This study analysed a subset of these children and included those who were recruited to the study at 9 years old (n = 8568). The ‘Diagnosed ADHD’ group included children with a clinical diagnosis of ADHD (n = 71). The comparator group (‘Undiagnosed ADHD’) comprised 9-year-old children with ADHD symptoms but with no formal diagnosis of ADHD (n = 582). Data were collected in two waves: the first when the children were aged 9 years (2007‒2008) and the second when the children were aged 13 years (2011‒2012).
The results show no significant differences between the Diagnosed ADHD and Undiagnosed ADHD groups for gender (male, 72.1% and 74.8%; female, 27.9% and 25.2%, respectively; p = 0.64), two-carer households (with 1‒2 children, 31.0% and 23.4%; with ≥3 children, 40.2% and 41.4%; p = 0.25), social class (p = 0.91), parental citizenship (Irish citizen, 92.4% and 96.1%; p = 0.30), parental education (p = 0.85) or income (p = 0.63).
Parents were asked to rate their child’s general health in the past year on a scale of 1 (very healthy) to 4 (almost always unwell). Children in the Diagnosed ADHD group suffered from worse general health at age 9 years than the Undiagnosed ADHD group (mean [standard deviation], 1.65 [0.59] vs 1.36 [0.53]; p < 0.001), although this difference was not significant by age 13 years (p = 0.63). At 9 years of age, 12.7% of children in the Diagnosed ADHD group had made ≥4 visits to a general practitioner in the previous year compared with 6.5% of children in the Undiagnosed ADHD group (p = 0.06). At 9 years old, there was no significant difference between the Diagnosed ADHD and Undiagnosed ADHD group in the proportion of children who had spent >2 nights in hospital over their lifetime (p = 0.34); however, there was a significant difference between these groups at 13 years old (p < 0.001), with more children in the Diagnosed ADHD group (56.7%) having spent >2 nights in hospital vs the Undiagnosed ADHD group (33.5%). Of the 9-year-olds with a clinical diagnosis of ADHD, 13.4% had been diagnosed in the last 6 months, 14.1% 6‒12 months ago, 19.7% 1‒2 years ago and 52.8% >2 years ago. Parent-rated hyperactivity/inattention was significantly higher for children in the Diagnosed ADHD group compared with the Undiagnosed ADHD group (p < 0.001); however, there were no differences between groups for teacher-rated hyperactivity/inattention (p = 0.59).
At 9 years of age, when controlling for hyperactivity/inattention symptoms, general health, cognitive ability and service engagement, there were no significant differences between the Diagnosed ADHD and Undiagnosed ADHD groups (p = 0.06). When controlling for these variables at 13 years of age, children in the Diagnosed ADHD group had worse scores in emotional (p = 0.01), peer relationships (p < 0.001) and prosocial behaviour (p = 0.02) scores as well as worse self-concept scores in terms of behavioural adjustment (p = 0.004), popularity (p = 0.01) and freedom from anxiety (p = 0.04) than those in the Undiagnosed ADHD group.
The relatively small number of cases of ADHD diagnoses (n = 71) is a limitation of this study and may have adversely affected the power of the analysis to detect differences at 9 years of age. The authors suggested that this may be due to parental under-reporting. This low prevalence may also represent a culturally conservative approach to psychiatric diagnoses in children in Ireland, and families of children with behavioural dysfunction may have also been less likely to participate in the study.
In concluding, the authors noted that the children in this study who were diagnosed with ADHD fared worse than their peers with no diagnosis of ADHD, but presented with similar symptoms and behaviours. The authors suggested that more studies may be needed to explore how a diagnosis of ADHD may affect development of socio-emotional characteristics, and how this can be impacted by a child’s biological, familial or educational backgrounds.
O’Connor C, McNicholas F. What differentiates children with ADHD symptoms who do and do not receive a formal diagnosis? Results from a prospective longitudinal cohort study. Child Psych Hum Dev 2020; 51: 138-150.