ADHD doesn’t have a single cause; instead, a person develops the condition when many different factors are aligned. Still, a growing number of studies suggest that brain differences found in people with ADHD are heavily influenced by genetics. These changes in one’s DNA are passed down from one generation to another.
ADHD runs in families
It has long been observed that ADHD has a strong hereditary component – meaning that having a parent, sibling, or another close family member with ADHD increases the chance of a diagnosis. Usually, this suggests that genetics is at play, in addition to environmental factors. “Based on the results of family and twin studies, the estimated heritability of ADHD approximates 80%, suggests a significant genetic component,” states a 2022 review published in Frontiers of Psychology.
That said, the same study also points out that the exact pattern of inheritance of ADHD is unknown. The medical community tends to agree that the effect of genetics is manifested via an increased likelihood of ADHD instead of its certain development. In that regard, the genetic risks of ADHD are more comparable to something like hypertension rather than Down Syndrome – as described in an American Psychiatric Association (APA) meta-analysis.
Researchers are aware of dozens of gene variations in people with ADHD, most of which remain unidentified. In the Time publication titled Growing Up with ADHD, Dr. Russell Barkley, a clinical professor of psychiatry and pediatrics, listed 25-45 of such genetic variations. The majority of these genes are believed to carry a small contribution, and most individuals with ADHD have several of them.
Genes That Contribute to ADHD
Admittedly, knowledge of the genetic architecture of ADHD is currently limited. Still, studies were able to pinpoint several clusters of genes linked with ADHD. They can be categorized along the brain functions they regulate, namely:
1. Neurotransmitters ensure communication between neurons. Several genes involved in the functioning of the neurotransmitter dopamine are closely linked with ADHD. When the brain is low on dopamine, it can lead to motivation issues, inattention, and problems with emotional regulation - all of which are common signs of ADHD.
2. Brain development - genes that govern the growth and organization of neurons.
3. Uncommon mutations in genes or chromosomes - very rarely, ADHD can be a part of a more extensive neurodevelopmental condition. A 2018 meta-analysis lists five such syndromes. Usually, these conditions develop early in life and cause other symptoms - both psychiatric and not.
In addition to specific genetic anomalies, researchers also point out that identical twins have a higher chance of developing ADHD; a person with an identical twin diagnosed with ADHD is almost certain to have the condition. Interestingly, this likelihood is much lower for non-identical twins - studies report.
A word for those with a family history of ADHD
While it is true that having a family member with ADHD increases one’s likelihood of having ADHD, it is by no means cast-iron certainty. Currently, there are no genetic tests for identifying one’s predisposition to ADHD. Therefore, looking out for symptoms of ADHD (if they emerge at all) is vital for a happy and fulfilling life, as are organizational techniques that can be accessed through coaching, psychotherapy, or various programs and tools tailor made for navigating life with ADHD.