Three symptom categories are associated with Attention Deficit Hyperactivity Disorder (ADHD): inattention, agitation, and impulsivity. An individual who exhibits symptoms in these three categories is considered to be affected by ADHD. However, an individual who only exhibits inattention symptoms is considered to be affected by Attention Deficit Disorder (ADD).
Attention deficit is a major part of both disorders, so similar supporting strategies will be used in both instances.
ADHD is an invisible condition. If no mitigation measures are implemented it will affect individuals from reaching their full potential.
Who has ADHD?
Between 4% and 8% of the general population struggles with ADHD, regardless of age or social status. According to some studies, this fraction can vary between 1% and 14.3%, regardless of where you are in the world. However, boys seem to be more susceptible to ADHD than girls, and they also tend to exhibit mostly symptoms of agitation and impulsivity, while inattention is the most prevalent symptom for girls.
For more details, please refer to the “Rapport du comité-conseil sur le Trouble de déficit de l’attention/hyperactivité et sur l’usage de stimulants du système nerveux central” (available in French only) published in 2000 by the ministère de l’Éducation of Quebec: Rapport du comité-conseil sur le Trouble de déficit de l’attention/hyperactivité et sur l’usage de stimulants du système nerveux central, gouvernement du Québec, Ministère de l’Éducation, 2000.
What causes ADHD?
Current scientific research seems to indicate that the cause of ADHD is neurobiological and genetic, although no biological marker has yet been found. Therefore, heredity is the most common cause of ADHD, according to various researchers (Barkley, 1998).
The high incidence of the disorder within a single family (10-35%) is well established, but recent studies (Biederman et al., 1995; Barkley, 1998)1 go further by showing that if a parent has the disorder there is a 57% chance of it developing in one of their children.
Barkley also mentions that genetic studies are underway to isolate the markers that may be linked with ADHD. The DRD4-7 gene has been found to be linked in some subjects, but further research is needed to find other markers.
There are also other causes that can explain the appearance of ADHD symptoms. Barkley points out that 10 to 15% of cases are the result of prenatal brain damage (exposure to smoking or alcohol, etc.) and that 3 to 5% of cases are result of postnatal brain damage (infection, head trauma, anoxia). However, while social factors may exacerbate the condition or contribute to its persistence, they cannot alone explain the occurrence of ADHD1.
Other interesting data…
Hyperactivity is biological in origin. It is caused by a neurotransmitter deficiency (especially dopamine), that leads the frontal lobe of the brain to slow down.
This deficiency is often hereditary and present from birth, although it is not noticeable until around age 4 or 5. Thirty-five percent of fathers and 17% of mothers of hyperactive children are themselves hyperactive. There is also a high probability that an uncle, aunt or cousins are also hyperactive. The hereditary nature of ADHD is reinforced by studies that show that the majority of identical twins share this trait2.
1. Ministère de l’Éducation, government of Quebec. 2000. Rapport du comité-conseil sur le Trouble de déficit de l’attention/hyperactivité et sur l’usage de stimulants du système nerveux central(hyperlien externe). Rapport du comité-conseil sur le Trouble de déficit de l’attention/hyperactivité et sur l’usage de stimulants du système nerveux central, gouvernement du Québec, Ministère de l’Éducation, 2000. 2. Dr. Guy Falardeau. 1992. Les enfants hyperactifs et lunatiques, comment les aider. Montreal: Le jour.