Children with a greater number of siblings receive later ADHD diagnosis than peers

Children with a greater number of siblings are more likely to receive a later diagnosis of attention deficit hyperactivity disorder (ADHD) than their peers, potentially hindering their educational and social development, new research published in the BMJ Evidence-Based Medicine reports.

In the largest study of its kind researchers from the University of Surrey investigated the age at which children are diagnosed with ADHD and what factors influence this. ADHD is the most common psychiatric disorder in children and adolescents; it is associated with difficulties in meeting developmental milestones, significant challenges in school, poor family and peer relations and low self-esteem. Early recognition of ADHD is critical as it helps experts address children's wide range of personal, social and educational needs.

Examining the records of 353,744 children under the age of 19 from 158 general practices in the Royal College of General Practitioners Research and Surveillance network, researchers identified 3,470 children with an ADHD diagnosis and determined that the average age of diagnosis was 10.5 years old, although there was a large variation across the country.

Researchers found that for every additional child in the household (more than two) there was a 27.6 percent increase in the age of the ADHD diagnosis. Additionally they found a correlation with parental age specifically that for every one year's difference between the age of the parent and the child in the household there was a 3.8 percent increase in the age of ADHD diagnosis.

Researchers believe that households with more children may delay parental recognition of an overactive child, and that older parents' greater parenting experience and skills can result in higher absorption of overactive behaviours.

Dr. Uy Hoang, Research Fellow at the University of Surrey, said: "It is important that more support and information is given to older parents and those with large families to help parents recognise the signs of ADHD. Early diagnosis of the condition is vital to the long term wellbeing of children, enabling them to access the support and resources they need. Busy family lives and strategies already in place to cope with overactive behaviour can distract from underlying issues that need medical attention."

Researchers also studied how general practices manage children with ADHD. Their data showed that general practices in more affluent areas are more likely to prescribe stimulants for children with ADHD than practices in poorer areas. Why this happens was not investigated in this study but researchers speculate that this may be due to parental pressure to medicate.

Researchers also found that larger practices with a small number of registered children were more likely to make the ADHD diagnosis at an older age than those with more children. This suggests that GPs in such practices may have less confidence in making early diagnosis, or require a higher threshold of symptoms to be presented during consultations. It could also reflect poorer links with specialist education services or child mental health services within the practice.

Professor Simon de Lusignan, Professor of Primary Care & Clinical Informatics at the Universities of Surrey and Oxford and principal investigator on the project, said: "ADHD affects all aspects of a child's life from how they learn at school to how they interact with peers. Left untreated, children can become isolated and frustrated, increasing their risk of depression. It is important that children with ADHD are diagnosed early to ensure that they receive the medical and educational care and support that they deserve."