Attention Deficit Hyperactivity Disorder
(ADHD · Attention Deficit Disorder · ADD)
In this condition factsheet:
The Facts on Attention Deficit Hyperactivity Disorder
Attention deficit hyperactivity disorder (ADHD) is a disorder that may be characterized by a pattern of inattention (inability to concentrate) sometimes combined with hyperactivity-impulsivity that is persistent, developmentally inappropriate, and occurs in at least two different settings.
ADHD affects 5% to 15% of school-aged children, occurring more frequently in boys than girls. ADHD may persist into adulthood in many cases. An inability to integrate in social, academic, or work-related settings is a pattern seen in people with a history of ADHD. In childhood, a person with ADHD may have academic problems, as the condition affects a person's ability to concentrate and focus on tasks. Because they are unable to organize their work or pay attention to their studies, children with ADHD may try to distract other children in class.
People with ADHD are especially sensitive to sensory stimuli such as noise, touch, and visual cues. They can easily be overstimulated, leading to changes in behaviour that may include aggressiveness.
Many people think ADHD and ADD (attention deficit disorder) are two different conditions, but they are in fact two names for the same condition. Other names no longer in use are minimal brain dysfunction (MBD) and hyperactivity.
Causes of Attention Deficit Hyperactivity Disorder
Biological causes are at the root of ADHD. Specifically, neurological imbalances in the brain are thought to be responsible for the symptoms exhibited by a person with ADHD.
In the brain, chemicals called neurotransmitters help send messages throughout the body. Scientific studies show that certain neurotransmitters are lower in quantity or are lacking in people with ADHD.
Even though the neurological imbalances are present in people with ADHD, the exact cause is unclear. In many cases, ADHD appears to be largely genetic, since children with ADHD are four times more likely to have close family members with the same medical condition, and it is much more common in identical twins than in non-identical twins or siblings. Scientific research has not yet discovered the chromosomes that may be responsible for the condition.
During pregnancy or after birth, certain factors may damage the brain and alter its function. During pregnancy, exposure of the baby's developing brain to radiation, alcohol, or other factors may lead to this condition. After birth, the development of certain infectious diseases that affect the brain tissue, such as meningitis or encephalitis, may affect the way the brain sends signals and contributes to the symptoms associated with ADHD.
Food additives and refined sugar are sometimes blamed as the cause of ADHD. Research shows that neither food additives nor sugar have any major effect on the symptoms of a child with ADHD.
Symptoms and Complications of Attention Deficit Hyperactivity Disorder
An attention deficit problem is officially described as a disorder when it is developmentally inappropriate and the symptoms first appear before the age of 7 and significantly interfere with functioning in at least two settings including school, work, family, or social life.
Symptoms of a child with ADHD fall into three large categories: inattention, hyperactivity, and impulsivity. They may include:
- fidgeting or squirming excessively
- having difficulty remaining seated
- being easily distracted
- not paying attention to details
- having difficulty organizing tasks
- being forgetful
- having difficulty awaiting his or her turn in games
- blurting out answers to questions
- having difficulty following instructions
- having difficulty sustaining attention
- shifting from one activity to another
- having difficulty playing quietly
- often talking excessively
- often interrupting
- often not listening to what is said
- often losing things
- often engaging in dangerous activities
There's no official symptom list for adults, but symptoms are similar to those listed above.
People with ADHD are much more likely to experience a number of other nervous system disorders. These may include:
- learning disabilities in 25% to 30% of people with ADHD despite normal intelligence
- tic disorders (such as Tourette's syndrome) in 20% of children with ADHD. More than 50% of children with Tourette's are also diagnosed with ADHD
- language problems, especially with expressive language (e.g., vocabulary)
- oppositional-defiant disorder
- conduct disorder
- autism
- anxiety disorders (25%)
- depression (20% to 30%)
Last reviewed: June 4, 2010
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