Biochemical Irregularities and Attention-Deficit Hyperactivity Disorder

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.

Parents of hyperactive-impulsive children with ADHD have referred to them as "unleashed tornadoes." They can't sit still, are disobedient, moody, rarely finish what they start, and have a hard time playing cooperatively for long periods of time. They run much of the time and never seem to wear themselves out, though their mothers and fathers are often worn to a frazzle. Parent tolerance for a child's activity level is influential in who does and doesn't get identified as having ADHD. For example, the mother of Jamar, an active toddler, may see him as hyperactive if she compares him to her three relatively placid daughters. The same child born into a boisterous, always moving family is seen as just another pea in the same pod.

Teachers report that in the classroom the hyperactive-impulsive child with ADHD disrupts others, can't stay on task for any length of time, has trouble following directions, gets frustrated easily, gets distracted when working in a group, and rushes into activities without thinking. These children are immature, have poor self-esteem, don't follow class rules, impulsively hit, injure themselves and objects around them, and have temper tantrums. Teacher tolerance level and the organization of the classroom (such as seatwork vs. small group activities) have a good deal to do with which child gets referred for an ADHD evaluation.

About 3 to 5 percent of children can be classified as having ADHD. It was once assumed that five to ten times as many boys as girls are hyperactive, but more recent evidence indicates that the ratio might be more equal. Because boys with ADHD tend to be more hyperactive, impulsive, and aggressive than girls, they more often get noticed and referred for evaluation. Among children with ADHD, various studies suggest that 20 to 40 percent have at least mild learning disabilities. Among students identified as learning disabled, various studies suggest that 15 to 30 percent can also be diagnosed with ADHD.

In contrast to the inattentive or hyperactive-impulsive child who is underfocused, there are children who have a problem because their attention is overfocused. Known as hypoactive, these children ponder too long, are overly attentive to details, and have a hard time making decisions. They are unmotivated, lethargic, sluggish, and need lots of sleep. Unlike their hyperactive classmates who, like it or not, occupy center stage, hypoactive children fade into the background and are often overlooked. In time, however, their slowness on assignments and difficulty with rapid responding get noticed. The Nichols and Chen National Collaborative Perinatal Project found that about 12 percent of children identified as learning disabled are hypoactive.