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Children with ADHD differ genetically from those diagnosed in adulthood

Summary: Children diagnosed with ADHD have a higher genetic overlap with autism spectrum disorder, while adults diagnosed with ADHD have a higher genetic overlap with depression.

Source: Aarhus University

Five percent of all school children in Denmark show symptoms of ADHD. For adults, it is about three percent. ADHD is a neurodevelopmental disorder that begins in childhood. Two-thirds of children who are diagnosed with ADHD continue to have ADHD into adulthood. In other cases, ADHD is not diagnosed until adulthood.

Researchers from the National Psychiatry Project iPSYCH studied the genetic differences between those diagnosed in childhood and those diagnosed in adulthood.

“We found that the genetic architecture differs depending on the age at which you are diagnosed when you receive an ADHD diagnosis,” says Associate Professor Ditte Demontis who initiated the study.

Less hyperactivity in adults

About 74% of the risk of being diagnosed with ADHD is caused by genetics. The genetics that cause ADHD are “polygenic,” which means that ADHD is caused by several genetic variants in the genome, each of which contributes slightly to the risk of developing the disease. Genetic architecture is the general term for all genome variants that contribute to ADHD.

In the new study, the researchers analyzed the genetic architecture of people diagnosed with ADHD as children and people diagnosed with ADHD as adults.

By comparing these results with the results of other large-scale genetic studies on autism and depression, the researchers found that the genetic architecture in children diagnosed with ADHD overlaps with autism much more than the genetic architecture people diagnosed in adulthood.

About 74% of the risk of being diagnosed with ADHD is caused by genetics. Image is in public domain

For people diagnosed with ADHD in adulthood, by contrast, the genetic architecture overlaps with the genetics of depression to a much greater degree than those diagnosed in childhood. This means that people diagnosed with ADHD in adulthood have an increased risk of depression partly due to genetic risk factors.

The researchers also found that the genetic architecture of people diagnosed with ADHD in adulthood had a lower load of genetic variants implicated in hyperactivity and inattention problems than people diagnosed with ADHD during childhood. childhood.

“In other words, people who are diagnosed with ADHD in adulthood are generally less genetically predisposed to be hyperactive and inattentive. This finding may help explain why the time of diagnosis occurred later in life. this particular group of people with ADHD,” says Ditte Demontis.

Taken together, these results suggest that there are differences in the underlying genetic architecture of ADHD depending on when you are diagnosed. The study results provide new insights into which diseases you have an increased genetic risk of developing based on when in life you receive your ADHD diagnosis.

About this genetics and ADHD research news

Author: Helle Horskjaer Hansen
Source: Aarhus University
Contact: Helle Horskjær Hansen – University of Aarhus
Image: Image is in public domain

Original research: Access closed.
Differences in Genetic Architecture of Common and Rare Variants in Childhood, Persistent and Late Diagnosed Attention Deficit Hyperactivity Disorderby Ditte Demontis et al. Natural genetics


Summary

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Differences in Genetic Architecture of Common and Rare Variants in Childhood, Persistent and Late Diagnosed Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that begins in childhood (ADHD in children); two-thirds of those affected continue to have ADHD in adulthood (persistent ADHD), and sometimes ADHD is diagnosed in adulthood (late-diagnosed ADHD).

We assessed genetic differences in children (not= 14,878), persistent (not= 1,473) and diagnosed late (not= 6,961) ADHD cases alongside 38,303 controls, and rare variant differences in 7,650 ADHD cases and 8,649 controls.

We identified four genome-wide significant loci for childhood ADHD and one for late-diagnosed ADHD. We found increased polygenic scores for ADHD in persistent ADHD compared to the other two groups.

Childhood ADHD had a higher genetic overlap with hyperactivity and autism compared to late-diagnosed ADHD and the highest burden of rare protein-truncating variants in evolutionarily constrained genes.

Late-diagnosed ADHD showed greater genetic overlap with depression than childhood ADHD and no increased burden in rare protein-truncating variants.

Taken together, these results suggest a genetic influence on age at first ADHD diagnosis, ADHD persistence, and different comorbidity patterns among groups.

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