The causes of ADHD are not known. However, it appears that heredity plays a major role in the development of ADHD. Children with an ADHD parent or sibling are more likely to develop the disorder. Before birth, ADHD children may have been exposed to poor maternal nutrition, viral infections, or maternal substance abuse. In early childhood, exposure to lead or other toxins can cause ADHD-like symptoms. Traumatic brain injury or neurological disorders also may trigger ADHD symptoms. Although the exact cause of ADHD is not known, an imbalance of certain neurotransmitters (the chemicals in the brain that send messages between nerve cells) is believed to be the mechanism behind ADHD symptoms.
A widely publicized study conducted by Ben Fein-gold in the early 1970s suggested that allergies to certain foods and food additives caused the characteristic hyperactivity of ADHD children. Although some children may have adverse reactions to certain foods that can affect their behavior (for example, a rash might temporarily cause a child to be distracted from other tasks), carefully controlled follow-up studies have uncovered no link between food allergies and ADHD. Another popularly held misconception about food and ADHD is that eating sugar causes hyperactive behavior. Again, studies have shown no link between sugar intake and ADHD. It is important to note, however, that a nutritionally balanced diet is important for normal development in all children.
People with ADHD suffer from a variety of symptoms. These symptoms include such things as distraction, not paying attention, inconsistency, forgetfulness of even simple tasks, fidgeting, verbal impulsivity, and so on. It is interesting to note that everyone suffers from these symptoms at times, but an individual with ADHD will have more of these symptoms more of the time.
Some doctors indicated immature symmetric tonic neck reflex (STNR) as a possible cause of certain symptoms. Other studies in 1993 and 1994 showed a link between the disorder and diet, dyes, and preservatives. In another study in 1996, ADHD was linked to maternal smoking during pregnancy.
Psychologists and other mental health professionals typically use the criteria listed in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) as a guideline for determining the presence of ADHD. For a diagnosis of ADHD, DSM-IV requires the presence of at least six of the following symptoms of inattention, or six or more symptoms of hyperactivity and impulsivity combined.
fails to pay close attention to detail or makes careless mistakes in schoolwork or other activities
has difficulty sustaining attention in tasks or activities
does not appear to listen when spoken to
does not follow through on instructions and does not finish tasks
has difficulty organizing tasks and activities
avoids or dislikes tasks that require sustained mental effort (like homework)
is easily distracted
is forgetful in daily activities
fidgets with hands or feet or squirms in seat
does not remain seated when expected to
runs or climbs excessively when inappropriate (in adolescents and adults, feelings of restlessness)
has difficulty playing quietly
is constantly on the move
blurts out answers before the question has been completed
has difficulty waiting for his or her turn
interrupts and/or intrudes on others
DSM-IV also requires that some symptoms develop before age seven, and that they significantly impair functioning in two or more settings (e.g., home and school) for at least six months. Children who meet the symptom criteria for inattention, but not for hyperactivity/impulsivity are diagnosed with Attention-deficit/hyperactivity disorder, predominantly inattentive type, commonly called ADD. (Young girls with ADHD may not be diagnosed because they have mainly this subtype of the disorder.)
Kim Sharp, Teresa G. Odle, The Gale Group Inc., Gale, Detroit,