A Deeper Genetic Understanding of ADHD
Our understanding of the genetic variations that underlie ADHD and seven other psychiatric disorders took a major step forward following the completion of a massive collaborative study promoted by the Psychiatric Genomics Consortium. The research results, published in the journal Cell, show 109 genetic variants associated with:
- ADHD
- Autism
- Depression
- Schizophrenia
- Bipolar disorder
- Obsessive-compulsive disorder
- Tourette syndrome
- Anorexia nervosa
Shared Genetic Variations and Comorbidities
The study comprised 230,000 patients with these conditions and a control group of 500,000 individuals. Researchers focused on the genes variations shared by multiple disorders, because it is common for multiple disorders to occur together in sequence over time. The findings offered some particular insights regarding ADHD:
- The research teams found that ADHD and depression share 44% of those genetic risk factors that are common in the general population. This helps explain why individuals with ADHD often suffer from major depression.
- The genetic insights from the study also provides further evidence that ADHD can persist over life, and be present in adults. As this becomes more widely understood, it reduce the social stigma regarding ADHD.
- Genes that are risk factors for more than one disorder are typically active during the second trimester of pregnancy, which is a critical period in the development of the nervous system.
- Sometimes the genetic variants can work in different directions. Thus they might be act as a risk factor one disorder, but be protective with respect to another. For example, a variant that is a risk factor for ADHD might protect the individual against anorexia nervosa.
- ADHD has a 75% genetic basis, with the remaining 25% being environmental factors, such as traumatic episodes during early childhood, toxins, etc..
A Clearer Picture
Now that the researchers have a better understanding of the genetic variations that contribute to ADHD, the next step is to look at the interplay between these genes and the environment. Future studies planned by the Psychiatric Genomics Consortium will focus on the effects of environmental impacts on DNA via epigenetic mechanisms like DNA methylation.
Ultimately, the idea is to use genetics to improve the diagnosis, prognosis and treatment of ADHD and other psychiatric disorders.