Using postmortem brain tissue, a new study investigates the genetic variations between individuals with attention deficit hyperactivity disorder.
National Institutes of Health researchers have successfully found changes in gene activity in the brains of ADD patients (ADHD). Scientists from the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health (NIH), discovered that individuals diagnosed with ADHD have variations in genes that code for known brain cell communication molecules. The findings, which were published in Molecular Psychiatry, demonstrate how genetic differences may contribute to symptoms.
This is the first study to evaluate ADHD using postmortem human brain tissue. The non-invasive scanning of the brain, which permits researchers to analyze the anatomy and activation of brain regions, is an additional method for examining mental health disorders. However, these studies lack information regarding the genes and how they may influence cell function and cause symptoms.
The researchers utilized a genomic technique known as RNA sequencing to investigate gene expression, or how certain genes are switched on or off. The caudate and the frontal cortex, two related brain areas associated with ADHD, were examined. These regions are believed to play a crucial role in attention management. Prior research has revealed changes in the anatomy and function of certain brain areas in ADHD patients.
ADHD is one of the most prevalent mental health diseases in the United States, affecting around one in ten children. Often diagnosed throughout childhood, symptoms may remain until maturity. Individuals with ADHD may be energetic and have trouble concentrating and controlling impulses, which may interfere with their ability to complete everyday chores and maintain concentration at school or work.
Researchers have been able to identify genes associated with ADHD as a result of technological breakthroughs, but they had not been able to understand how genetic changes in these genes lead to symptoms until now.
This study was led by Gustavo Sudre, Ph.D., associate investigator in the Social and Behavioral Research Branch of the Intramural Research Program at the National Human Genome Research Institute. “Multiple types of genomic investigations indicate to the expression of the same genes,” he stated. “Intriguingly, these changes in gene expression were identical to those observed in other conditions, which may reflect differences in how the brain processes in autism.”
Importantly, the researchers discovered that these changes influenced the expression of genes that code for neurotransmitters, the chemicals used by brain cells to interact. Specifically, the data indicated variations in the gene expression of glutamate neurotransmitters, which are essential for cognitive processes such as attention and learning.
“The work increases our understanding of ADHD by demonstrating that the disorder is associated with alterations in the expression of certain genes in the brain. This brings us closer to understanding how genetic differences affect gene expression in the brain and contribute to ADHD symptoms, according to Philip Shaw, M.D., Ph.D., senior investigator in the Social and Behavioral Research Branch, who oversaw the study.
Postmortem studies are uncommon due to the limited availability of donated brain tissue, yet they are highly significant since they allow researchers immediate access to the brain for experimental purposes.
“Such postmortem studies have expedited our understanding of other mental health disorders,” said Dr. Shaw, “but until today, no such studies have examined ADHD.”
Andy Baxevanis, Ph.D., and Derek Gildea, Ph.D., from NHGRI’s Bioinformatics and Scientific Programming Core; Laura Elnitski, Ph.D., NHGRI senior investigator; and the Human Brain Collection Core at the National Institute of Mental Health, which is led by Stefano Marenco, Ph.D., were essential to the success of this study.
The National Human Genome Research Institute (NHGRI) is one of the 27 institutes and centers that make up the National Institutes of Health (NIH), a branch of the Department of Health and Human Services. The Division of Intramural Research of the National Human Genome Research Institute develops and implements technologies to investigate, diagnose, and cure genomic and genetic diseases. Additional information about NHGRI can be found at: https://www.genome.gov.
About the National Institutes of Health (NIH): The National Institutes of Health (NIH), the nation’s medical research organization, consists of 27 Institutes and Centers and is part of the U.S. Department of Health and Human Services. The NIH is the principal government organization that conducts and supports basic, clinical, and translational medical research and investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.