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 behavior 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.
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.