ADHD stands for Attention Deficit/Hyperactivity Disorder. The disorder is characterized by attentional problems (“attention deficit”) as well as hyperactivity (“hyperactivity”). Although public opinion seems to emphasize more on the hyperactivity part, it is not the case that ADHD patients are only hyperactive. A lot of people suffering from ADHD have mainly attentional problems, also called ADD. In science, and on this website, we refer¬ to “inattentive subtype” or “ADHD-I”. Next to this subtype, there is the hyperactive and impulsive subtype or “ADHD-H”. Impulsivity, or problems with inhibiting impulses is an important characteristic of ADHD too. Finally, there is the combined subtype of ADHD, in which attentional problems as well as hyperactivity and impulsivity are present. This subtype is also called ADHD-C

ADHD does not only affect children, also adults can have the disorder. Although a lot of children overgrow their ADHD symptoms, a substantial part of them remain symptomatic. ADHD in adults is called persistent ADHD, which alludes on the presence of ADHD symptoms in childhood as well as in adulthood. It is estimated that persistent ADHD affects 2,5 to 5% of the adult population.

ADHD is heritable. This means that, if you have family members suffering from ADHD, there will be a vast chance that you will suffer from the disorder too. Next to this, we know that persistent ADHD is more heritable than ADHD that is only present in childhood. What we actually do not know very well, is which genes exactly play a role in the development of ADHD. Genes are tiny little bits of heritable material. You get them from your parents. These tiny bits contain information that determine, for example, the color of your eyes. Genes also have influence on how our brain functions. Via our brain, genes also influence partly our behavior. Because there is a huge variability in genes, we are all different. Some people have blue eyes, while others have brown eyes. It is known that variations in some genes are more common in people who have ADHD compared to people without ADHD. Therefore, we think that these genes have something to do with the development of ADHD. Through research, we want to investigate how these genes can be of influence in causing ADHD.