In a groundbreaking development in the field of neurodevelopmental disorders, researchers have identified certain genetic variants that are common to both autism and ADHD, two of the most common child psychiatric diagnoses. They have also discovered five gene variants that are unique to either of these diagnoses. This could have a significant impact on how we understand, diagnose, and treat these disorders, according to the researchers.
Anders Børglum, Professor at the Department of Biomedicine at Aarhus University and iPSYCH, Denmark’s largest research project within psychiatry, was part of the team behind the study. “We have succeeded in identifying both shared genetic risk variants and genetic variants that differentiate the two developmental disorders,” he says in a statement.
The professor explains that this achievement begins to shed light on “the biological processes that are behind the development of both diagnoses,” and uncovers the processes that specifically push a developmental disorder towards either autism or ADHD.
These genetic variants influence nerve cells in the brain, affecting how the brain develops and communicates. Interestingly, some of these genetic variants also impact people’s cognitive functions.
Børglum elaborates on this, stating, “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.”
Additionally, the study highlighted a gene variant that increases the risk of autism while reducing the volume of a specific brain area in the general population. Its counterpart increases the risk of ADHD while simultaneously increasing the volume of the same brain area.
Genetic risks in ADHD and autism patients
The study, published in Nature Genetics, is a pioneering effort in illustrating that individuals diagnosed with both autism and ADHD bear a double genetic risk for these disorders. In contrast, those diagnosed with only one of the conditions typically only carry the genetic risk variants for that specific disorder.
“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,” Børglum clarifies.
This groundbreaking discovery will allow the medical community to develop more precise diagnoses, implement earlier interventions, and ensure that the appropriate treatment is provided to each patient.
Historically, an autism diagnosis is usually made before an ADHD diagnosis, potentially overshadowing any ADHD symptoms. However, Børglum suggests that by studying the genetic profile of a person with an autism diagnosis and identifying a high genetic load of ADHD genes, clinicians may better monitor the individual for potential ADHD symptoms, allowing for earlier detection and support.
Only a few years ago, it wasn’t possible to diagnose ADHD in a person who had autism due to an official diagnosis hierarchy. The new study, however, lends substantial biological evidence to the revised diagnostic guidelines of the American Diagnosis and Classification system for Mental Disorders (DSM-5), which now allows for a dual diagnosis.
“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,” concludes Børglum.
