Why is ADHD a Syndrome?
Once the diagnosis of Attention Deficit Hyperactivity Disorder is suggested in a child, many parents scrutinize the 18 DSM-IV criteria and reflect that many of these symptoms could be describing ordinary childhood behavior. A common discussion I have with parents involves explaining why symptoms of ADHD are different than ordinary childhood behaviors. This is an important discussion. I need to have very good justification for putting a child on powerful psychiatric medication, and the presentation of syndrome of ADHD can range from subtle to very obvious. Additionally, the scientific community has evolved in its understanding of what symptoms are part of this disorder. Society came to formally recognize the assortment of symptoms that today comprises ADHD as a psychiatric illness slowly, and the disorder has been called by many different names. Like many psychiatric illnesses, the diagnosis of ADHD has an interesting history. In this entry I'd like to discuss some of that history and how it has come to be understood as an illness in the scientific community.
First, there is some vocabulary to discuss. ADHD is considered a syndrome. The word syndrome come from the Greek roots syn (together) and dromos (running). A syndrome is usually defined as a collection of signs and symptoms that appears associated with some sort of abnormal, pathologic, or disease process. The word "sign" is a finding made by a physician and a "symptom" is something that a patient experiences. So pain felt by a patient in their abdomen is a symptom but an abnormal heartbeat heard through a stethoscope is a sign. The word "disease" is also defined by a set of signs and symptoms but also either has consistent anatomical changes or a generally recognized agent that has caused the signs and symptoms.
A syndrome, therefore, is primarily descriptive, while a disease has a description and either a physical finding or a known cause. Many disorders start out as syndromes then should technically be known as diseases, but for one reason or another (tradition, common use, etc.) the syndrome name sticks. For example, Acquired Immune Deficiency Syndrome (AIDS) is still so named even though it's been many years since researchers have discovered the human immunodeficiency virus (HIV) as the causative agent. A connective tissue disorder Ehlers-Danos Syndrome (EDS) is still so named even though the specific mutations of the specific genes that result in the illness have been found.
Syndromes are characterized by a list of signs and symptoms that are considered typical, but often there are findings that are associated with the disorder but not considered part of it. For example, 50% of children with the ADHD have a second psychiatric disorder. In these situations, it can be quite tricky to determine which symptom is caused by which disorder. For example, in a child who has both ADHD and depression it can sometimes be difficult to tell whether the inattention the child is experiencing is due to ADHD or depression.
We do not yet know the cause of ADHD, so I think it will still be considered a syndrome for some time. However this does not mean the symptoms are any less real, the suffering experienced by the child and family is any less intense, or that the treatment is any less effective. In my next entry I will discuss how the understanding of what constitutes ADHD has evolved in the psychiatric community since the early 1900's. Please note that you should talk to your physician if you have specific questions or concerns about the diagnosis and treatment of ADHD in yourself or a loved one.