Did you know that ADHD and autism share genes?
Researchers from the Danish national psychiatric project iPSYCH have found that the two disorders share changes in the same genes.
The knowledge relates directly to the biological causes of both child psychiatric disorders.
In Denmark, approximately one per cent of schoolchildren have autism and two to three per cent are diagnosed with ADHD.
Different disorders, common symptoms
Autism and ADHD are different developmental disorders, but can have some common symptoms.
For example, children with autism can demonstrate violent or aggressive behavior, be impulsive, and have problems in school and with social relations.
Children with ADHD can share the same symptoms.
Researchers from iPSYCH discovered the similarities between the two diagnoses can be linked to changes in the same genes.
It was the largest study to date of rare mutations in the genome of people with ADHD and autism.
“The very fact that mutations are found to the same extent and in the same genes in children with autism and in children with ADHD, points towards the same biological mechanisms being involved,” says Anders Børglum, a professor at Aarhus University, principal investigator at iPSYCH and a leading researcher in the study.
The findings of the research, carried out in collaboration with the Broad Institute and Harvard, were published in the international journal Nature Neuroscience.
First time a gene is linked to ADHD and autism
“This is the first time that the genome has been mapped so comprehensively for both ADHD and autism,” says Anders Børglum.
“The discovery that children with ADHD have the same amount of deleterious gene mutations in their DNA as children with autism is both striking and quite surprising.”
The findings point directly towards which biological causal mechanisms are shared by the two disorders.
The MAP1A gene
“In the study, the gene that is most frequently affected by mutations in people with ADHD or autism is the so-called MAP1A gene,” Børglum explains.
“The [MAP1A] gene is involved in the formation of the physical structure of nerve cells — their inner ‘skeleton’, so to speak — and is important for the development of the brain.”
This is the first time that this gene has been linked to the development of these two disorders. The mutations found by the researchers give a significantly increased risk of developing one or both disorders.
“We discovered an increased burden of mutations that destroy or severely affect the MAP1A gene in those with ADHD and autism, while very few of the control subjects had such changes in the gene,” Børglum explains.
This means that the risk of ADHD and autism increases by more than 15 times for people who carry a mutation in the MAP1A gene.
Using DNA to find ADHD & Autism
The researchers analyzed the genes of approximately 8,000 people with autism and/or ADHD, and 5,000 people without either of the two disorders, all from Denmark.
The study also incorporated additional data from approx. 45,000 international control subjects who did not have any psychiatric disorders.
People born in Denmark between 1981 and 2005 were matched with diagnoses of autism, ADHD and mental retardation.
“The study shows that many more genes for ADHD and autism can be identified directly by studying more people in a similar way with extensive DNA sequencing, thereby providing a more complete picture of the biological causal mechanisms and possible approaches to medical treatment,” the researcher explains.
As part of the project, Anders Børglum and his colleagues had access to samples from the Danish National Biobank at the Statens Serum Institut and data from the Danish Psychiatric Central Research Register.
F. Kyle Satterstrom, Raymond K. Walters, Tarjinder Singh, Emilie M. Wigdor, Francesco Lescai, Ditte Demontis, Jack A. Kosmicki, Jakob Grove, Christine Stevens, Jonas Bybjerg-Grauholm, Marie Bækvad-Hansen, Duncan S. Palmer, Julian B. Maller, Merete Nordentoft, Ole Mors, Elise B. Robinson, David M. Hougaard, Thomas M. Werge, Preben Bo Mortensen, Benjamin M. Neale, Anders D. Børglum, Mark J. Daly. Autism spectrum disorder and attention deficit hyperactivity disorder have a similar burden of rare protein-truncating variants. Nature Neuroscience, 2019; 22 (12): 1961 DOI: 10.1038/s41593-019-0527-8
Hana Julian is a licensed clinical psychotherapist specializing in ADHD across the life span, offering teletherapy sessions. Email TheJerusalemTherapist@gmail.com or send a WhatsApp text to +972-54-310-1933 for a free consultation.