Biochemical changes linked to ADHD

A difference in protein distribution, important for attention and learning among children with ADHD, has been found in a study done at the Swedish Örebro University. The difference in distribution of the protein is nearly 50 percent lower than what is normal. Due to this find, scientists believe that there are links between ADHD and other biochemical disturbances which has previously been disputed.

Jessica Johnsson, one of the Örebro University scientists, claim that this find could pave the way for other drugs than the ADHD drugs in use today. Johnsson presents these findings in her dissertation in medicine, belonging to the Experimental Neuropsychiatric group.

The group has mapped changes in the cells that are believed to cause ADHD and other disorders.

The leader of the group, is Nikolaos Venizelos, claims: “Very low levels of important signal substances in the brain are believed to case many of the diseases and impairments we study, which is why our understanding of these disorders increase when we understand how these changes occur.”

Various amino acids are transported to the brain to produce signal substances such as dopamine, noradrenaline and serotonin. When the group of scientists studied the capacity of connective tissue cells to transport these signal substances, they can see how whell this transportation is working. They finally found that the transport of tryptophan is lower in children with ADHD, compared to children who don’t have the disorder.

They claim that this could mean that the brain doesn’t produce as much serotonin, which is important to balance the mood of an individual. Without this knowledge, we might have missed signs of depression and mood swings in children with ADHD. An addition of serotonin could be necessary for successful treatment of ADHD.

The least expected discovery in this research, according to Nikolaos Venizelos, was how drastically reduced the amount of the acetylcholine receptor is in children with ADHD. It works as a protein which recieves the signal substance acetylcholine, which is necessary for concentration and learning. The acetylcholine effect is also noticed in pations suffering from Alzheimer’s, where it is treated with existing drugs. Thanks to these findings, it is possible that ADHD can be treated partly with existing methods used for other diseases and disorders.

Since there are similarities between ADHD and bipolar disorder, the team has studied biochemical chances in that disorder as well. In those cases, the primarily reduced signal substance production is that of dopamine and noradrenaline. Since both these disorders share a lack of amino acid transport, this might be the genetic link to find the cause of the disorder. The research team now hopes not only to give way to new drugs for ADHD, but also to be able to point the way towards new methods of diagnose, which could prevent wrongful diagnosis and medication.

Tim Fawcett

Meet the author

Dr. Tim Fawcett has a Ph.D in behavioral sciences and works at the Institute of Biological and Environmental Sciences at the University of Aberdeen, in Scotland. He has conducted and co-authored several scientific studies regarding child health, ADHD and bipolar disorder. He also publishes articles for, to reach a wider audience.