How Are Genetic Risk for ADHD and Autism Related to Children's Cognitive Abilities?

What you need to know

Higher genetic risk for ADHD was associated with worse working memory performance in school-aged children.
This association was only found at the initial assessment, not in how working memory changed over time.
The link between ADHD genetic risk and working memory was stronger in boys than girls.
Genetic risk for autism was not significantly related to the cognitive measures examined.

Understanding ADHD, Autism, and Cognition

Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are neurodevelopmental conditions that begin in childhood. While they are distinct disorders, ADHD and ASD share some common features, including:

Early onset in childhood
Alterations in brain development
More common in males
Often accompanied by cognitive difficulties

Children with ADHD frequently struggle with working memory and maintaining consistent focus. Working memory refers to the ability to hold information in mind and work with it for short periods. For example, remembering a phone number long enough to dial it uses working memory.

Some individuals with autism may have cognitive strengths in certain areas, but many also experience challenges with working memory and attention. These cognitive difficulties can persist even in people who don’t meet full diagnostic criteria for ADHD or ASD.

Genetics and Cognition

Previous research suggests that ADHD, ASD, and cognitive abilities like working memory may have some shared genetic influences. This means that some of the same genetic variants that increase risk for ADHD or autism may also affect cognitive skills.

To explore this further, researchers can use a technique called polygenic risk scoring. This involves looking at many genetic variants across a person’s genome to calculate their overall genetic risk for a particular trait or disorder.

The current study used polygenic risk scores to examine how genetic risk for ADHD and ASD relates to cognitive performance in children from the general population.

The Current Study

Researchers analyzed data from 1,667 school children aged 7-11 years in Spain. The children completed computerized tests of working memory and attention four times over the course of a year.

Working memory was assessed using a task where children had to remember sequences of letters or numbers. Attention was measured by looking at how consistently children responded during a computer task.

The researchers calculated polygenic risk scores for ADHD and ASD for each child based on their genetic data. They then looked at how these scores related to the children’s performance on the cognitive tests.

Key Findings

ADHD Genetic Risk and Working Memory

Children with higher polygenic risk scores for ADHD tended to perform worse on working memory tasks at the initial assessment. This was true for both verbal working memory (remembering words) and numerical working memory (remembering numbers).

Interestingly, ADHD genetic risk was not related to how working memory changed over the course of the year. Children improved their performance similarly regardless of genetic risk.

The association between ADHD genetic risk and working memory was stronger in boys compared to girls. When analyzing the sexes separately, the relationship was only statistically significant for boys.

Autism Genetic Risk and Cognition

Polygenic risk scores for autism were not significantly related to working memory or attention performance in this study. There was a hint that higher autism genetic risk might be associated with slightly faster improvement in verbal working memory over time, but this finding was not statistically robust.

Attention Performance

Neither ADHD nor autism genetic risk scores were significantly associated with the measure of attention used in this study.

Implications

These findings suggest that some of the same genetic factors that increase risk for ADHD may also contribute to difficulties with working memory, even in children without an ADHD diagnosis. This genetic overlap appears to be stronger for boys than girls.

The lack of association with how working memory changed over time implies that ADHD genetic risk may affect a child’s starting point, but not necessarily their capacity to improve with age or practice.

For autism, this study did not find clear evidence that common genetic risk variants are related to working memory or attention performance in the general child population. More research is needed to understand how autism genetics may relate to cognitive strengths and challenges.

Limitations

Some limitations of this study include:

The sample size was relatively small for genetic research.
The study only looked at a 1-year period of cognitive development.
Autism symptoms were not directly measured in the participants.

Conclusions

Common genetic variants linked to ADHD risk may contribute to working memory difficulties in school-aged children.
This relationship appears to be stronger in boys than girls.
ADHD genetic risk did not predict differences in cognitive development over a 1-year period.
More research is needed to clarify potential links between autism genetics and cognitive performance.

Understanding these genetic connections may eventually help identify children at higher risk for cognitive challenges and allow for earlier support. However, it’s important to remember that genes are not destiny - many other factors influence a child’s cognitive development and academic success.