ADHD - definitions, the history, causes, prevalance, subtypes

1. 1 Definitions of ADHD

ADHD is an acronym standing for attention deficit hyperactivity disorder, which, at times, is referred to as ADD. Over the last century this neurobehavioral problem has been known by several names such as: minimal brain damage, minimal brain dysfunction, hyperkinetic reaction of childhood, attention deficit disorder (ADD) with or without hyperactivity and many others.
ADHD is a disorder manifested in various ways. Research of the 70s and 80s of the twentieth century identified clear diagnostic criteria and provided a number of definitions of this disorder. Definitions of ADHD collected from a number of sources by Rief (2005:3) give the best description of the nature of the disorder:
• “ADHD is a neurobiological behavioral disorder characterized by chronic and developmentally inappropriate degrees of inattention, impulsivity, and, in some cases, hyperactivity” (cited in Rief 2005:4; ChADD, 2001c).
• ADHD is a brain-based disorder that arises out of differences in the central nervous system- both in structural and neurochemical areas.
• ADHD is a neurobiological behavioral disorder causing a high degree of variability and inconsistency in performance, output, and production.
• ADHD is a dimensional disorder of human behaviors that all people exhibit at times to certain degree. Those with ADHD display symptoms to a significant degree that is maladaptive and developmentally inappropriate compared to others that age.
• ADHD is a developmental of self-control, consisting of problems with attention span, impulse control, and activity level (cited in Rief 2005:4; Barkley, 2006).
• ADHD is a chronic physiological disorder that interferes with a person’s capacity to regulate and inhibit behavior and sustain attention to tasks in developmentally appropriate ways.
• ADHD refers to a family or related chronic neurobiological disorders that interfere with an individual’s capacity to regulate activity level (hyperactivity), inhibit behavior (impulsivity), and attend to tasks (inattention) in developmentally inappropriate ways (cited in Rief 2005:4; National Institute of Mental Health, 2000 National Resource Center on ADHD, 2003a).
• Attention-deficit/hyperactivity disorder is the most common neurobehavioral disorder of childhood. ADHD is also among the most prevalent chronic health conditions affecting school-aged children (cited in Rief 2005:4; American Academy of Pediatrics, 2000).
• ADHD is a neurobehavioral disorder characterized by differences in brain structure and function that affect behavior, thoughts, and emotions (cited in Rief 2005:4).
• ADHD is characterized by a constellation of problems with inattention, hyperactivity, and impulsivity. These problems are developmentally inappropriate and cause difficulty in daily life. (cited in Rief 2005:4; Goldstein, 1999).”
All of the above definitions indicate that any learning problems attributed to lack of attention or any behavioural problems displayed by ADHD children are the result of neurobiological malfunction in their brain.

1. 2 The History of ADHD

Research on ADHD dates back to the beginning of the twentieth century, being first recognized by George Still in 1902. This famous English pediatrician examined a group of children who displayed some behavioral problems as well as an inability to focus attention. Still’s observation of inattentiveness, inclination towards behavioral overreaction, as well as resistance to discipline among these children made him conclude that they suffered from a “lack of moral control”, which was manifest in their poor control of inhibition and aggressive behavior. He further concluded that these behavioral problems arouse from a biological malfunction that was nested inside a child to the exclusion of external factors such as poor parenting or adverse environmental conditions (Green and Chee 1994:13).
By the late 50s of the twentieth century the term “minimal brain damage” had been in use to describe what is today known as ADHD. The name however put a great deal of attention on the nature of this disorder, and not on the symptoms. From the 50s onward the word “hyperactivity” became synonymous with ADHD and was frequently used to describe it.
Many influential researchers supported the idea of analyzing symptoms as the means leading toward the explanation of the nature of ADHD. It has been discovered that the main symptom among the examined is a concentration problem, and not hyperactivity. The current term, ADHD, was adopted in 1994 by the American Psychiatric Association (O’Regan 2005:12-13).

1.3 The description of ADHD

1.3.1 Prevalence of ADHD

Statistics concerning the frequency of occurrence of ADHD defer and are dependant on which portion of population has been examined, the geographical location of the research, and the criteria used. Rief (2005:14) quotes some data connected with incidences of ADHD:
• Approximately 3 to 5 percent of school-aged children are afflicted with this disorder.
• The American Academy of Pediatrics and National Initiative for Children Healthcare Quality (in 2002) estimated the number of school-aged children suffering from ADHD at 4 to 12 percent.
• About 7 percent of the American primary school students have been diagnosed with the disorder – these are the findings of a 2002 nationwide survey conducted by the Center for Disease Control and Prevention. The American Psychiatric Association placed this figure at 3 to 7 percent.
• According to Murthy and Barkley (1996:22), the number of adults affected by ADHD oscillates around 2 to 4 percent.
• Due to the nature of this disorder, the symptoms are usually carried from childhood into adolescence, and approximately 67 percent of people affected will carry them into adulthood (CHADD, 2003a).
Based on the recent data, Munden and Arcelus (2006:51) estimate that in Poland the number of individuals afflicted with ADHD is in the neighborhood of 10-15 percent. Professor Tylor has gathered data concerning the occurrence of ADHD in Britain, according to which 1.7 percent of the entire British population suffer from ADHD in its severe form.
ADHD is mostly a “boy” problem. According to J. Dupaul and Stoner, boys with the disorder outnumber girls in clinical cases (a 6:1 ratio) and community (a 3:1 ratio). Many young females may not display behavioral problems and therefore be never diagnosed with the disorder since girls, by nature, are much less disruptive than boys. Nevertheless, they may still suffer the consequences of ADHD in their overall school performance (Green and Chee 1994:6). Mundane and Arcelus (2006:51) believe that ADHD is much easier identifiable in boys than girls due to the more open exhibition of aggressive behavior and overreaction. Approximately 50 percent of the affected children receive a psychotropic treatment, about 12 percent receive special education, and about 34 percent use mental health services (Dupaul and Stoner 2003:4), which makes ADHD a high incident disorder prevalent mostly among males.
ADHD is a lifelong disorder and as such it requires the services of many professionals over an extensive period of time to produce some positive developmental outcomes (Dupaul and Stoner 2003:4).
Studying the statistical data, it becomes obvious that ADHD is not confined to any specific geographic location, and in its non-discriminatory nature it may affect the entire human population.

1.3.2 The causes of ADHD

Although ADHD has been studied extensively in a number of countries all over the world and a number of scientific studies are still in progress, as of yet the findings have not identified a clear single cause of the disorder. Unfortunately, the modern science is still unable to fully understand this problem. Nevertheless, based on the conducted research, it can provide some probable causes, which include heredity, pre- or postnatal trauma, lower metabolism in certain brain regions, chemical imbalance or deficiency in neurotransmitters, minor brain differences, or environmental factors (Rief 2005: 17-19). ADHD is a biological condition which is not caused by home environment, too much TV, food allergies, excess sugar or poor home life or poor schooling. On the other hand, these factors are likely to contribute to a behavior that may resemble the typical ADHD symptoms.
Despite a number of theories trying to explain the causes of ADHD, there is still much to learn about this disorder, which is yet another puzzle for the scientists to solve, hopefully, in the near future.

1.3.3 Subtypes of ADHD

The symptoms of ADHD vary from individual to individual. For instance, children affected by the disorder can show a wide range of difficulties with attention, while others may be mildly inattentive but overly impulsive. Some individuals may be overactive, whereas others may demonstrate under-active behavior. Still others may have problems in many areas such as inattention, impulsivity, and hyperactivity.
ADHD symptoms have been divided into three subtypes, which is the typology used by Dupaul and Stoner (2003:8):
1. Predominantly inattentive type – ADHD-IA which is identified by at least six inattention symptoms but less than six hyperactive-impulsive symptoms.
2. Predominantly hyperactive-impulsive type – ADHD-HI which is identified by at least six hyperactive-impulsive symptoms but less than six inattention symptoms.
3. Combined type (inattention, impulsivity, and hyperactivity) – ADHD-CT which is identified by at least six of the nine inattention symptoms and at least six of the nine hyperactive –impulsive symptoms.

The predominantly inattentive type of ADHD

This is the most widespread, frequently called a classical type referred to as ADD. It describes children with a great number of inattentive symptoms, who can also display some degree of hyperactivity and impulsivity. ADHD-IT is very often overlooked both by parents and teachers since the affected children may not display disruptive behaviors that would draw attention to a potential problem. Instead the symptoms may be interpreted as a lack of interest on the part of these students and as such they might be translated into poor academic performance. This type of ADHD may be identified by a number of characteristics that are prevalent in afflicted students at the above-the-average level.
According to Rief and the DSM IV and DSM-IV-TR (2005: 4-5) the most common and typical symptoms of inattention are easiness with which a student is distracted by extraneous stimuli, appearance that a student is not listening when spoken to, difficulty remembering and following directions, difficulty sustaining attention during various activities, difficulty sustaining level of alertness to tasks, forgetfulness in daily activities, not following instructions and failure to finish schoolwork, daydreaming, confusion, easiness in becoming overwhelmed, difficulty starting tasks, reluctance to engage in tasks requiring mental efforts, difficulty working independently, getting bored easily, poor study skills, no attention to details resulting in careless mistakes, inconsistent performance – “consistently inconsistent”, disorganization, loss or misplacement of things as well as no awareness of time.
Rief (2005:6) identifies a wide array of problems that ADHD students may experience in their academic performance such as losing track, focus, forgetting information, skipping words during their reading activities, having problems with planning and organizing their written assignments, writing off topic, poor spelling, punctuation, and editing skills, or poor problem solving skills and computational errors in math.

The predominantly hyperactive - impulsive type of ADHD

It is present in individuals with a significant number of hyperactive-impulsive symptoms, who may have some or none of the inattentive symptoms. Children affected by this type exhibit behaviors that far exceed what is considered to be normal behaviors for children at a given age, both in intensity as well as frequency.
The most common and typical symptoms of hyperactivity are overactivity reflected in “as if driven by a motor” behavior, inability to sit still during task activities, high energy level, running around, jumping, climbing in inappropriate situations, unnecessary movement, restlessness, fidgeting, squirming, roaming around the classroom, noisiness, invading other people’s space, inability to calm down.
To the most typical symptoms of impulsivity belong no patience, excessive talkativity, interrupting other students, answering questions before tasks have been completed, inability to sit calmly, acting before thinking, noisiness, acting as if consequences do not exist, engagement in high risk situations, breaking things, disrupting others, resorting to violence, lack of willingness to go back to previously completed tasks, making careless mistakes, always in a hurry, becoming easily bored with tasks.
Apart from these symptoms, Rief (2005:8) lists some other characteristics present in children afflicted with ADHD, which include: excessive emotionality, easy outburst of frustration, quick reaction and overreaction, discipline difficulty, lack of willingness to work on long-term goals, low self-esteem, poor handwriting and written production skills, oversensitivity to sounds, touch, etc., poor motivation, or lack of motivation, poor academic performance, underachievement as well as communication problems.
ADHD may appear in various forms and shapes in different children. Some cases may seriously impede the child’s development, while others may affect it mildly. For this reason each individual afflicted by ADHD is different. It is a mistake to believe that the child with this syndrome would have no talents, interests, or some positive personal traits.
Occasionally, all people exhibit this type of behavior, however, with ADHD students, the frequency as well as intensity are relatively much higher. ADHD is a chronic disorder, which can occur early in life and be present throughout the adulthood. It may have an adverse effect on academic achievements, on the personal conduct of an individual among his family or his peers (O’Regan 2005:12).

1.4 Some disorders that co-exist with ADHD

Hyperactivity, impulsivity, and inattention are not the exclusive symptoms of ADHD but are characteristic of other medical conditions, which very often leads to misdiagnosis. Typically, two-thirds of children affected by ADHD have also some other associated disorders, which Rief (2005:12) enumerates as follows: oppositional defiant disorder: 30-65%; anxiety disorder 20-35% of children, 25-40% of adults; conduct disorder 10-25% of children, 25-50% of adolescents, 20-25% of adults; bipolar (maniac/depressive illness) 1-20%; depression 10-30% of children, 10-47% of adolescents as well as adults; tics/Tourette’s syndrome approximately 7% have tics or Tourette’s syndrome; learning disabilities 12-60%; sleep problems over 50% of children have a problem falling asleep, 40% may have problems with night-walking; secondary behavioral complications about 65% of children may exhibit noncompliance, argumentativeness, bad temper, lying, etc.
Based on the conducted research, Munden and Arcelus (2006: 27) enumerate the following learning difficulties that children with ADHD may have. These are inability to cope with learning about 90%, underachievement 90%, poor reading skills 20% and poor writing skills 60%.
This information might be valuable especially to teachers and healthcare providers who, by the nature of their work, should be aware of these associated disorders.