Attention-deficit hyperactivity disorder (ADHD) is a mental health condition that can cause unusual levels of hyperactivity and impulsive behaviors. It is one of the most common neuropsychiatric conditions that begin in childhood and usually continues through adulthood.  People with ADHD may also have trouble focusing their attention on a single task or sitting still for long periods of time. 

Many people experience inattention and changes in energy levels, but for a person with ADHD, this happens more often and to a greater extent compared with people who don’t have the condition. It can have a significant and harmful effect on their studies, work and home life. 

A wide range of behaviors including having trouble focusing or concentrating on tasks; being forgetful about completing tasks; losing things frequently; being easily distracted; having difficulty sitting still; and interrupting people while they’re talking are associated with ADHD. 

Treatment for the condition typically includes behavioral therapies, medication or both. ADHD medications are designed to affect brain chemicals in a way that enables you to better control your impulses and actions.

Despite how common ADHD is, doctors and researchers still aren’t sure what causes the condition; they believe it has neurological origins and may have a genetic role. Although there is a known hereditary predisposition to this phenomenon, the genetic-molecular basis for it is only partially known. 

But now, researchers from Soroka University Medical Center and Ben- Gurion University (BGU) of the Negev in Beersheba have uncovered a molecular genetic mechanism responsible for ADHD. The research was conducted as part of Daniel Halperin’s doctoral dissertation under the supervision of Prof. Ohad Birk, director of the Human Genetics Institute at Soroka and at BGU’s Kahn Laboratory.

In a new article in the prestigious journal Nature Communications under the title “21 CDH2 mutation affecting N-cadherin function causes attention-deficit hyperactivity disorder in humans and mice,” the Beersheba researchers have shown that a mutation in a single gene called CDH2 can cause ADHD in humans.

Furthermore, the introduction of the human mutation in the corresponding gene of the mouse in genetic engineering technology caused hereditary hyperactivity in mice.

The CDH2 gene encodes the N-cadherin protein, which is known for its activity in making and connecting brain cell connections. The study demonstrated that the mutation in CDH2 impairs the activity of this protein, thereby altering brain regions known to be involved in ADHD. Using a study of the neurons of the mice in which the human mutation was introduced, the researchers demonstrated the exact effects of the mutation in CDH2 on nerve cell conduction.

The team discovered the gene in three siblings, one a singleton and the others premature twins, born to a couple of who are first cousins. The three children had severe ADHD that was diagnosed by the age of three. They were very hyperactive and impulsive. 

Birk explained that “beyond the scientific importance of a clear characterization of a genetic basis and a new molecular mechanism for ADHD, the research findings and models created in cell and mouse lines allow new directions for the development of new drugs for ADHD,” and the team is beginning to investigate the possibility of creating new drugs.