The complexities of the human brain and its underlying genetic and biological mechanisms are truly fascinating. A recent study by scientists at Aarhus University sheds new light on the genetic factors underlying attention-deficit/hyperactivity disorder (ADHD), a common neurodevelopmental disorder affecting millions of people worldwide.
By studying over six million genetic variants in nearly 40,000 people with ADHD and almost 187,000 without ADHD, the researchers identified 27 genetic risk variants for the disorder. These risk genes are expressed in the brain and neurons, particularly dopaminergic neurons, which play a role in reward response and the concentration of dopamine in different brain regions.
The Importance of the Study
The study is groundbreaking because it finds more than twice as many risk variants as previous studies and provides new knowledge about which tissues and cell types are particularly affected in individuals with ADHD. Moreover, the genetics that increase the risk of ADHD also affect genes expressed in other mental disorders such as autism, depression, and schizophrenia. Interestingly, the vast majority of the risk variants have an influence on multiple disorders, which suggests common underlying biological mechanisms among these disorders.
The researchers also found that ADHD should be seen as a brain developmental disorder influenced by genes that have a major impact on the brain’s early development. These genes have a high level of expression in a wide range of brain tissues, even at the embryonic stage.
The study indicates that an increased load of ADHD risk variants in an individual’s genome is associated with reduced reading and mathematical abilities, reduced attention, and reduced short-term memory.
The Future of Research
While this study provides valuable insights into the genetic mechanisms underlying ADHD, there is still much to be learned. The researchers have only mapped a small fraction of the common variants that influence ADHD, and larger genetic studies are needed. Moreover, it is important to undertake studies that focus on identifying how the genetic risk variants perturb biological processes in the brain cells, their way of joining up, and communicating with each other in the brain. Brain cells and early developmental stages of the brain, so-called mini-brains or brain organoids, are currently being examined.
The study highlights the importance of large international collaborations involving experts from different fields such as genetics, psychiatry, psychology, epidemiology, molecular biology, statistics, bioinformatics, and computer science. By studying the genetic causes of psychiatric diseases and neurodevelopmental disorders, we can gain a better understanding of the biological mechanisms underlying these disorders and identify new drug targets to treat them.
Just as the universe is infinitely complex and constantly evolving, so too is the human brain, and the study of ADHD is an important step towards unraveling its mysteries.
Uncovering The Genetic Roots Of ADHD: How Early Brain Development And Dopamine Play A Role
By Mark Pierce | February 23rd 2023 08:09 AM | Print | E-mail
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