ADHD children have higher genetic overlaps with autism spectrum disorders than adults with ADHD. Adults with ADHD also have higher genetic overlaps with depression.
ADHD symptoms are present in five percent of Danish schoolchildren. It is approximately three percent for adults.
Researchers at the national psychiatry program psych studied the genetic differences in people who were diagnosed as children and those who were diagnosed as adults.
Associate Professor Ditte demontis, who led the research, said that genetic architecture can differ depending on age.
Adults are less hyperactive
Genetics account for approximately 74% of ADHD cases. ADHD can be caused by multiple genetic variants. Each genetic variant contributes slightly to the disease’s risk. The term genetic architecture refers to all variants of the genome that are responsible for ADHD.
Researchers analyzed the genetic structure of ADHD patients diagnosed as children and adults in the new study. These results were compared with other large-scale genetic studies on autism and depression. The researchers found that children with ADHD have a genetic architecture that overlaps significantly with adults.
Genetics account for approximately 74% of ADHD risk.
However, individuals with ADHD as adults have a genetic architecture that overlaps with the genetics for depression to a greater degree than people who were diagnosed as children. People with ADHD as adults are at greater risk for depression because of genetic risk factors.
Researchers also discovered that people with ADHD who have been diagnosed as adults had lower levels of genetic variants associated with hyperactivity and inattention than those with ADHD in childhood.
in other words: people with ADHD who are adults are less likely to be hyperactive or inattentive because of their genetic predispositions. This may explain why ADHD diagnosis was made later in life for some people, Ditte Demontis explains.
These results indicate that ADHD is a complex genetic disorder with different genetic features depending on the time you were diagnosed. Based on your ADHD diagnosis at a later age, the results of this study reveal new information about which diseases you are more likely to develop.