Biochemical Irregularities and Attention-Deficit Hyperactivity Disorder

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Several biochemical irregularities can lead to learning disorders in children who otherwise have good potential to learn. Some of these biochemical disturbances can cause severe brain injury. Others create problems with attention and hyperactive-impulsive or hypoactive states that make it particularly hard for the child to focus and sustain attention. Although bothersome, the activity level among hyperactive- impulsive children is not really important; the real problem is that these children can't concentrate long enough on important information to learn effectively.

Many children with learning disabilities, more often girls than boys, have subtle attention deficits that are easy to overlook because the children do not cause behavioral problems in the classroom. In situations that require sustained attention and sitting still, however, children who are also hyperactive and impulsive are sure to be noticed. It might be hard to pick out a hyperactive youngster on the playground without watching carefully for the number of activity changes, problems entering and negotiating a game, and what happens when he doesn't get his way; but place the same child in the classroom and his attention shifts, overtalkativeness, and moving around are glaring.

One study revealed that hyperactive-impulsive children don't actually get up and down more often in the classroom than their peers, but they do so at inappropriate times. For example, they hop up and cross the classroom for a toy in the middle of a reading group. They can't help being distracted or dim the impulse to move toward what distracted them, even when they know it's not the right time or place. As a group these children are marked by their inappropriate activity, restlessness, impulsivity, distractibility, and poor concentration. Teachers say that the only thing consistent about them is their inconsistency.

Attention deficits seem to be at the root of these children's learning difficulties, whether the type of deficit is primarily inattentive, hyperactive-impulsive, or both. In official jargon, all are said to suffer from attention-deficit hyperactivity disorder (ADHD). The DSM-IV recommends that all the following conditions be met before a diagnosis of ADHD is confirmed:

• Many symptoms of the disorder are present
• The symptoms are severe enough to impair academic and/ or social functioning
• The symptoms are inconsistent with the child's developmental level
• The symptoms have persisted six months or more
• The symptoms were present before 7 years of age
• The symptoms are observed both at school and at home
• There is no evidence of a health condition or mental illness that could cause similar problems

At least 11 different physiological hypotheses have been put forward to account for inattention and hyperactivity. This chapter concentrates on biochemical irregularity, which causes extremely short attention span, distractibility, and poor impulse control that become evident early in life and persist from year to year. Other causes of inattention and hyperactivity include genetic predisposition, brain injury, maternal smoking during pregnancy, lead poisoning, chromosomal anomalies, anxiety, emotional disturbance, stress, boredom, and temperament.