Polygenics and ADHD — What South African Parents Should Know

As parents, it’s natural to want clear answers about why your child may struggle with focus, impulsivity, or hyperactivity. You might hear that ADHD “runs in families” and wonder: Is there a gene for ADHD? The short answer is no. But, there is a powerful genetic influence.

ADHD is what scientists call a polygenic condition, meaning it arises from the combined effect of many genes, each contributing a small part of the picture.

In recent years, researchers have developed tools called polygenic scores or polygenic risk scores (PRS) that aim to capture this combined genetic influence. These scores are becoming more common in scientific studies of ADHD, and parents may encounter them in the media or even in commercial genetic testing.

What does “polygenic” mean?

“Polygenic” simply means “involving many genes.” Unlike conditions caused by a single gene mutation (like cystic fibrosis or Huntington’s disease), ADHD arises from the small contributions of hundreds or thousands of common genetic variants.

Each variant might only shift risk by a fraction of a percent, but when combined across the genome, they add up. ADHD also involves complex interactions with environment: sleep, nutrition, trauma, school setting, and family context all influence how these genetic predispositions manifest.

Researchers have shown that ADHD is highly heritable, with family and twin studies suggesting around 70–80% of the variation is influenced by genetics. But heritable doesn’t mean predetermined: genes set a backdrop, not a destiny.

How are polygenic scores calculated?

Here’s a simplified step-by-step:

1. Genome-wide association studies (GWAS): Scientists analyse the DNA of hundreds of thousands of people, some with ADHD and some without.
2. Identify small signals: They look for tiny differences in DNA frequency between the two groups.
3. Weight the variants: Each DNA location (called a SNP, or single-nucleotide polymorphism) is given a weight based on how strongly it is linked to ADHD.
4. Add it up: For any individual, scientists can total these weighted variants to produce a single polygenic score.

The higher the score, the higher that person’s relative likelihood of ADHD, compared to the population studied. It’s important to emphasise: a high score does not mean a child will definitely have ADHD, just as a low score does not rule it out.

What do polygenic scores tell us right now?

1. Useful for groups, not individuals

Polygenic scores are most valuable in research. They can explain a modest portion of ADHD differences between groups — around 5–10% in the best studies. But this is far too small to act as a diagnostic tool for a single child.

2. Links to related traits

ADHD polygenic scores are correlated with other outcomes. Studies have found associations with learning difficulties, body mass index, and even brain structure differences. This helps scientists trace shared biological pathways.

3. Combined approaches look promising

A 2024 study showed that using polygenic scores together with behaviour checklists improved identification of children at risk of ADHD traits. This doesn’t replace a professional diagnosis, but it points to how genetics could support screening tools in future.

Can polygenic scores be used in clinic today?

Not yet. There are three main reasons:

1. Predictive limits
   Polygenic scores simply aren’t strong enough to predict ADHD at the individual level. Many children with high scores will never develop ADHD, and many with low scores still do.
2. Population differences
   Most GWAS data comes from people of European ancestry. This matters because polygenic scores often perform poorly when applied to children from different backgrounds. South Africa is highly diverse, so scores developed overseas may not apply here. This makes direct-to-consumer genetic testing risky.
3. Ethical concerns
   Using genetic risk scores in children raises questions of privacy, stigma, and misuse. There is currently no ethical or clinical framework in South Africa to guide their use in diagnosis or school decisions.

Why are researchers excited?

Despite current limits, scientists see several possible future applications:

• Early support
  PRS might one day help identify children who would benefit from monitoring or early interventions, especially when combined with teacher reports or cognitive testing.
• Better understanding of comorbidity
  Polygenic studies show ADHD shares biology with learning differences, mood conditions, and sleep issues. This could eventually guide tailored interventions.
• Personalised medicine research
  In the future, clinical trials may use PRS to test whether certain interventions work better for children with specific genetic profiles.

At present, all of this remains research, not clinical practice.

What parents need to know

1. Diagnosis is still clinical
   ADHD is diagnosed through thorough assessment by professionals — paediatricians, psychologists, psychiatrists, or multidisciplinary teams. Genetic scores cannot replace this.
2. Genetics is not destiny
   A polygenic score is about probability, not certainty. Environmental factors, parenting strategies, school accommodations, and health interventions have enormous influence.
3. Beware of direct-to-consumer tests
   Some companies may claim to “predict ADHD” through DNA. Parents should be cautious: these tests may be based on non-diverse data and lack medical validity.
4. Focus on proven strategies
   Sleep routines, structure, behavioural supports, school accommodations, and, when prescribed, medication are all evidence-based supports for children with ADHD. These make a difference now, regardless of genetic score.

In South Africa, there are currently no clinical services offering polygenic scoring for ADHD as part of routine care. Families may encounter overseas testing companies marketing such services online, but these should be approached with caution.

Our population’s unique genetic diversity — including African, European, and mixed ancestries — makes it vital that local research expands before polygenic tools can be meaningfully applied here. Until then, diagnosis and treatment should follow established pathways: clinical assessment, supportive interventions, and family-centred care.

Polygenics gives us a powerful lens on the complex biology of ADHD. It confirms what many parents already see: that ADHD is not caused by “bad parenting” or “laziness” but has deep biological roots. At the same time, genetic risk is not destiny. The right supports, environment, and interventions can make a huge difference.

As the science develops, The Neuroverse will continue to share updates relevant to South African families. For now, parents should feel reassured: while researchers explore genetics, your focus can remain on the practical supports that help your child thrive today.

References and further reading…

1. Demontis D et al. Dissecting the polygenic contribution of attention-deficit/hyperactivity disorder. Nature Genetics. 2024.
2. Using polygenic scores in combination with symptom rating scales to identify ADHD. BMC Psychiatry. 2024. https://bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-024-05925-7
3. Du Rietz E et al. Association of Polygenic Risk for Attention-Deficit/Hyperactivity Disorder with Cognitive Functioning and Educational Attainment. Am J Psychiatry. 2018. https://pmc.ncbi.nlm.nih.gov/articles/PMC6278881/
4. Li JJ, He Q. Polygenic scores for ADHD: A meta-analysis. Research on Child and Adolescent Psychopathology. 2021. https://pubmed.ncbi.nlm.nih.gov/33492530/
5. Lázaro L et al. Polygenic risk and clinical presentation of ADHD: A review. J Psychiatr Res. 2022. https://www.sciencedirect.com/science/article/abs/pii/S0022395622004083