Large systematic review on how genetic risk for ADHD is associated with a wide variety of outcomes

Polderman, de Bode and Ronald conducted the first systematic review on the association between a genetic risk for Attention Deficit/Hyperactivity Disorder (ADHD) and a variety of outcomes. The study details the results from 44 studies that were published between 2018 and 2021 and contain information from more than 200,000 subjects. Outcome measures were classified into meaningful categories.

ADHD is a common condition that affects approximately one in 20 children and one in 50 adults. It is characterised by symptoms of hyperactivity, inattentiveness and impulsivity. It can severely affect individuals and their families in a variety of ways including relationships, schooling and behaviour.  There is an urgency to develop accurate biological and causal models of ADHD in order to devise effective early intervention and treatment options. 

The results of the study show that a genetic risk for ADHD is predictive for an ADHD diagnosis in independent samples. Yet, the ADHD PRS is also associated with a range of other outcomes such as brain structure, education, and socio-economic status. Polderman: “So far, we knew these associations mostly of epidemiological studies, we now show that part of these associations may have a genetic basis".

The impressive number of included studies ensured that for each outcome category multiple studies contributed, and subsequently rather firm conclusions could be drawn. "Based on standardized criteria we could conclude that evidence was strong for an association with ADHD, externalizing mental problems, physical measures such as BMI, brain and neuropsychological measures, education, and socio-economic measures", clarifies Polderman. To their surprise, the authors did not observe a strong association with substance use and autism, while their co-occurrence with ADHD in epidemiological studies is evident. 

This study is important as in the future, it may be possible to use a variety of characteristics to help predict who will develop ADHD. Early detection is important because individuals could then benefit from early  interventions such as additional support during the preschool years, additional support  for parents, support with lifestyle features such as sleep habits and diet, and tailored support in school. The polygenic score for ADHD may in the future be one of these characteristics that is used in combination with other factors, such as family history, to identify individuals who are likely to develop ADHD. 

The study is open access available to everyone interested as Ronald A, de Bode N, Polderman TJC. Systematic Review: How the Attention-Deficit/Hyperactivity Disorder Polygenic Risk Score Adds to Our Understanding of ADHD and Associated Traits. Journal of the American Academy of Child and Adolescent Psychiatry, 2021, Read the article.