What Causes Attention Deficit Disorder?

Information on Attention Deficit Disorder (ADD) the underlying causes of this disorder.

(this article does not summarize the latest on ADHD)

Attention Deficit Disorder (ADD) is one of the most frequently clinically referred psychological disorders in children. It can occur with (more common) or without hyperactivity, and has a higher incidence in male children. The disorder typically onsets by age 2 or 3 years, but help is generally not sought until these children enter school and experience difficulties. This article will examine what ADD is and its possible causes.

As infants, sufferers may be colicky, irritable and difficult to manage (Barkley, 1985), and inability to maintain attention is the central characteristic of ADD. Impulsivity (which suggests poor self-control, excitability and inability to delay gratification or inhibit urges) and overactivity (parents and teachers often comment that these children cannot sit still) are also evident. They also have social difficulties (Cunningham et al., 1980) and they are often referred to as immature, uncooperative, self-centered and bossy. Aggressive behaviors, reading difficulties and other academic problems are also common.

The prognosis is not good - children with ADD tend to carry their academic and social problems into adulthood, when some may improve, but the vast majority experience life-long problems.

ADD has been recognized since 1902 when it was referred to as hyperactivity, but extensive research into this condition did not begin in earnest until the 1960s. Since then, there has been a boom in the amount of research that has been carried out in this area.

There have been major disagreements in the diagnosis of ADD - mainly between the American and European scientific communities:

1. The Americans have defined ADD as a situational disorder (the symptoms depending on the circumstances the child is in), while the British see it as a pervasive disorder (these children are overactive in all situations)

2. Americans are more likely to diagnose ADD, while the British are more likely to give a diagnosis of Conduct Disorder.

3. Americans believe that the diagnosis of ADD should only be given if the child's IQ is over 70, while the British say the IQ should be less than 70 before such a diagnosis is given.

4. American and British professionals are thus different with regard to how they label this disorder, and so, not surprisingly, the incidence of ADD is quoted at a higher rate (20% of the population) in America compared to the quoted incidence rate in Britain (1.6%).

Despite disagreements among medical and psychological professionals in different countries, there have been several theories put forward with regard to the possible causes of ADD:

1. Organic Brain Damage

The first suggestion about the possible cause of ADD was put forward in 1908 by Tredgold, who stated that hyperactivity was linked to organic brain damage which he believed was caused by injury, oxygen deprivation, prenatal complications or infection during birth.

Later research showed this theory to be flawed (Stewart and Olds, 1973) - most children with ADD do not show 'hard' signs of brain damage. Such damage may only be the case in 10% or less of this population.

There may, however, be a deficit in the metabolism of neurotransmitters (naturally occurring chemical substances in the brain). Stimulant drugs like methylphenidate (Ritalin) and dextroamphetamine (Dexedrine) have proved helpful in controlling the symptoms for some of these children. This suggests a 'brain chemical' causation. However, these drugs may only improve behavior in the short term and severe side effects including insomnia, loss of appetite and gastric problems have been observed.

Wender (1971) suggested that some children with ADD show signs of a defective inhibitory system in the limbic areas of the brain (which are directly involved in arousal and reward). This defective inhibitory system could manifest itself in overt symptoms of overactivity and the fact that ADD sufferers are less sensitive to the effects of reinforcements (rewards and punishments) so causing their inability to learn effectively. Other researchers have also suggested that these children may have an inability to modulate arousal, especially in new situations.

The evidence for widespread organic brain damage in these children is neither conclusive nor strong however.

2. Genetics

10% of ADD parents are also hyperactive and monozygotic twins have a higher correlation of them both exhibiting the disorder than do dizygotic twins. There is also some evidence (Morrison and Stewart, 1971, 1973) of psychiatric disturbance in the biological (and not the adoptive) parents of ADD children.

3. Environmental factors

Artificial colors in various food stuffs, lead levels in the atmosphere, environmental pollution and fluorescent light levels have all been implicated as possible causes for ADD. However, the experiments investigating these factors have typically been poorly designed. There is some evidence, however, that special diets (e.g. the Feingold diet, 1975 - which restricts artificial food coloring, flavorings and natural salicylates) can 'work' for some sufferers. There has also been evidence that sugar (e.g. in fizzy drinks) can amplify the hyperactive behavior.

4. Family factors

Battle and Lacey (1972) suggested that their studies indicated that the mothers of children with ADD tend to be critical, disapproving, not affectionate and may use severe punishment. Today, however, it is generally agreed that this type of behavior from the mother is more likely to be a reaction to their child's behaviors rather than the cause of the behavior per se (Weiss and Hechtman, 1986). The problem here is that the arguments tend to be circular - cause and effect are difficult to separate, especially because the children with this disorder tend not to be 'labeled ADD' until they reach school age - seven or more years have elapsed and early mother-infant interactions are not available for analysis.

Jacobvitz and Sroufe (1987) did examine child-mother interactions from an early stage however and discovered that the mothers care-giving style tended to be intrusive and interfering, with the mother not giving the child any opportunity to process and manipulate environmental stimuli for himself (at an early stage). Care giving then became more 'seductive' by 24 months (where mothers of these children kissed them a lot and teasing at this inappropriate stage was commonplace). By 42 months, mothers in the study were found to be over stimulating their children.

It is clear however that much more research needs to be carried out before any 'real' conclusions can be drawn. If parenting style is important then parents could be given assistance with regard to coping with and managing their child's behaviors.

In summary, the exact causes of ADD are not known, but it is believed that many of these 'possible causes' interact in a complex fashion to make a child vulnerable to this disorder.

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