Is there a genetic overlap between ADHD and autism? Attention deficit hyperactivity disorder (ADHD) & autism spectrum disorder (ASD) often share certain genes and genetic variants.
- Autism and ADHD are more likely to share some common genetic burden
- Seven similar genetic variants of autism and ADHD are identified
- Identifying both shared genetic risk variants and genetic variants that differentiate the two developmental disorders can lead to better diagnosis and treatment
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Researchers have now identified seven genetic variants that are common to both autism and ADHD, as well as five gene variants that are specific to only one of the two diagnoses.
“We have succeeded in identifying both shared genetic risk variants and genetic variants that differentiate the two developmental disorders,” says Professor Anders Børglum of the Department of Biomedicine at Aarhus University and iPSYCH, Denmark’s largest research project within psychiatry, which is behind the study.
“That means that we are beginning to understand both the biological processes that are behind the development of both diagnoses, and – as something completely new – also the processes that push the developmental disorder specifically in the direction of either autism or ADHD.”
Role of Genes in ADHD and Autism
The genetic variants affect nerve cells in the brain and the way the brain develops and communicates. It is also remarkable that some of the genetic variants identified also have an impact on people’s cognitive functions in general in the population.Specifically, the researchers can for example see that some of the genetic variants that only increase the risk of autism also increase the cognitive functions of individuals, while the complementary variants, which only increase the risk of ADHD, generally reduce the cognitive functions of individuals.
It may seem obvious, but the study is the first in the world to show that people with both ADHD and autism are double-burdened with a genetic risk of receiving both diagnoses, whereas people who only have one of the diagnoses for the most part only bear the genetic risk variants for this one condition.
Importance of ADHD and Autism Diagnosis
“This means, for example, that people with both diagnoses have both an equally large load of ADHD genetic factors as people who only have ADHD, and at the same time the same large load of autism genetic factors as people who only have autism. So it makes very good biological sense that some people have both diagnoses,” says Anders Børglum.“The autism diagnosis is typically made before an ADHD diagnosis. So if, for example, the person is also hyperactive and finds it difficult to concentrate, this may well be slightly drowned out by the autism symptoms, and we may not see the ADHD challenges,” explains Anders Børglum.
“But if we have a genetic study of a person with an autism diagnosis, and we see a major genetic load of ADHD genetics, then it may be that we should monitor that person a bit more closely. In this way, we can in the future become quicker to spot the development and give the family good tools to handle this diagnosis, too. “
A few years ago – due to an official diagnosis hierarchy – it was not in principle possible to diagnose ADHD in a person who had autism, he says.
“But now we have shown that people with both diagnoses are in fact double burdened with the genetic risk of both developmental disorders. There is thus a clear biological difference between whether you have both diagnoses, or just one. The study is therefore a strong biological argument for the revised diagnostic guidelines, e.g. in the American Diagnosis and Classification system for Mental Disorders (DSM-5), where it is now possible for the same person to receive both diagnoses,” says Anders Børglum.
“This is the first step. Here and now, the study is relevant because it helps to create a better understanding of the causes of the two developmental disorders, and in the long term, this can form the basis for better diagnostics and treatment.”
Reference:
- Identification of shared and differentiating genetic architecture for autism spectrum disorder, attention-deficit hyperactivity disorder and case subgroups - (https://www.nature.com/articles/s41588-022-01171-3)
Source-Eurekalert