Does ADHD cause dyslexia, or is it the other way around? And what about dyscalculia? These conditions have puzzled parents, teachers, and researchers for years. It’s common to see children struggling not just with attention problems (ADHD), but also experiencing difficulties in reading (dyslexia) or math (dyscalculia). But how often do these conditions really co-occur, and why?

A recent large-scale study involving nearly 20,000 Dutch twins provides essential insights into these questions. Researchers Elsje van Bergen and her colleagues looked at the co-occurrence of ADHD, dyslexia, and dyscalculia among children aged 7 and 10. They found that while these conditions indeed appear together more frequently than expected by chance—children with ADHD were more than twice as likely to also have dyslexia or dyscalculia—most children actually had only one of these challenges. Specifically, about 77% of children with one condition had no additional learning difficulties.

But here’s the twist: despite common assumptions, ADHD doesn’t directly cause dyslexia or dyscalculia, nor do these learning difficulties directly lead to ADHD. Instead, the study suggests these conditions often appear together due to shared genetic factors. Certain genes increase a child’s susceptibility to multiple developmental challenges, influencing how the brain processes information, attention, reading, and math skills.

The researchers noted an interesting exception between reading and spelling abilities, where a clear causal connection was identified: better reading skills directly improved spelling over time. However, this causal relationship didn’t extend to math or ADHD symptoms.

These findings are crucial, especially for educators and clinicians. If ADHD and learning difficulties are mainly genetically linked rather than causally related, it means interventions should specifically target each condition separately. Treating ADHD, for instance, won’t automatically solve dyslexia or math problems, and vice versa.

This study also carries an important message for parents. Knowing that these conditions share genetic roots helps reduce misplaced guilt or blame. Recognizing the genetic nature of ADHD, dyslexia, and dyscalculia can foster greater understanding and support for children facing these challenges.

Ultimately, while ADHD, dyslexia, and dyscalculia often travel together, they do so because of common genetic risks—not because one condition inevitably leads to another. Understanding this helps us tailor more effective and compassionate approaches in education and intervention.

Abstract of the study:

ADHD, dyslexia, and dyscalculia often co-occur, and the underlying continuous traits are correlated (ADHD symptoms, reading, spelling, and math skills). This may be explained by trait-to-trait causal effects, shared genetic and environmental factors, or both. We studied a sample of ≤ 19,125 twin children and 2,150 siblings from the Netherlands Twin Register, assessed at ages 7 and 10. Children with a condition, compared to those without that condition, were 2.1 to 3.1 times more likely to have a second condition. Still, most children (77.3%) with ADHD, dyslexia, or dyscalculia had just one condition. Cross-lagged modeling suggested that reading causally influences spelling (β = 0.44). For all other trait combinations, cross-lagged modeling suggested that the trait correlations are attributable to genetic influences common to all traits, rather than causal influences. Thus, ADHD, dyslexia, and dyscalculia seem to co-occur because of correlated genetic risks, rather than causality.