Friday, September 01, 2006

Causes and Effects of One Disruptive Behaviour

Point 4: AD(H)D

In general there are three categories under which the most common ADHD behaviours fall: inattention, hyperactivity, and impulsivity.


People who are inattentive typically have trouble keeping their mind on any one thing. They get bored easily, are often distracted by irrelevant stimuli, and don't seem to listen when someone is talking directly to them. Capable of devoting effortless attention to things they do enjoy, they find it extremely difficult to focus deliberate, conscious attention when it comes to other activities or to learning something new. This can lead to careless mistakes in schoolwork, failure to complete chores at home, or missed deadlines at work.


Hyperactive children always seem to be in motion physically or verbally. They may dash about, touch everything within reach, squirm in their seat, tap their toes, or chatter incessantly. They seem incapable of sitting through a lesson or a movie that doesn't captivate them with every scene. Hyperactive teens and adults may feel intensely restless most of the time.


People who are overly impulsive seem unable look before they leap. As children, they may dart into a street without watching for cars. Overly impulsive youngsters tend to find it very difficult to take turns or wait in line. They may grab a toy from another child or physically lash out when they are upset. As teens and adults, these individuals tend to interrupt what other people are saying or blurt out whatever springs to mind, even inappropriate comments.

Possible Causes-

Over the years, ADHD was thought to have been caused by diet, environmental toxins, food allergies, parenting practices, and prenatal or birth injuries. However more recent evidence indicates that for the most part, ADHD is caused by inherited factors which are manifest in abnormal brain morphology, and associated with an underlying neurological dysregulation and underarousal of the frontal lobes. One school of thought says that the cause of AD(H)D lies in a chronically over-aroused central nervous system resulting in the continual switching of attention. Other theorists suggest that, in fact, the opposite is true - chronic under-arousal results in the inability to maintain attention. The fact that AD(H)D is currently most successfully 3lled by the use of stimulant drugs such as Ritalin suggests that the latter explanation is the most plausible.

1) Family and environmental factors.

The behavioural view might suggest that ADHD results from poor parenting practices that reinforce inappropriate behaviours. Indeed some intervention therapies have assumed from the outset that ADHD is caused by dysfunctional family dynamics (Burte & Burte, 1994). The reverse could be argued, namely that ADHD behaviour causes the inappropriate parental responses. There is evidence for this argument in studies of the dynamics of families with ADHD children. Mothers for example, interact more dysfunctionally with their ADHD children than with their other children (Gomez & Sanson, 1994).

A 12 year follow-up study of ADHD children, who had received individual and residential treatment for their behaviours, showed that core deficits of the disorder persisted in more than half of the ADHD group. The ADHD group also experienced significantly more behavioural and academic problems in high school than did controls (Claude & Firestone, 1995). Other studies have shown that 75-80% of children with ADHD continue to experience academic difficulties and psychiatric problems into adolescence and adulthood.

Despite the existence of several intervention programs (Burte & Burte, 1994), it appears that there is a lack of evidence on the impact and effectiveness of behavioural treatments for ADHD, and substantial intervention outcome studies are scarce (Australian Psychological Society, 1997; Jarman, 1996). Hence, research does not appear to provide support for either a behavioural cause for ADHD, or for the long term effectiveness of behavioural intervention for ADHD.

2) Genetic evidence

In a study of 570 twins using objective measures of attentiveness and hyperactivity, genetic effects accounted for 50% of the observed variance, and the heritability for ADHD was estimated at 64% (Goodman & Stevenson, 1989). Although no specific gene has been identified as yet, there is strong evidence of a genetic involvement in ADHD (Hechtman, 1994).


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