Attention Deficit Hyperactivity Disorder

ADHD is a diagnosis characterized by behaviours showing inappropriate levels of inattention, impulsivity and hyperactivity. These behaviours appear in school, at home and in social situations, and typically become worse in situations where sustained attention is required (eg. doing seat-work, studying, listening to people talk). The behaviours associated with ADHD usually become apparent before the age of four, but are frequently not recognized until the child commences school. It is reported that up to 6 percent of children may show symptoms of ADHD, with males outnumbering females approximately three-to-one.


  • many of the behaviours/characteristics of ADHD are present in all children to some degree and at particular ages;
  • the behaviours are not abnormal in themselves - only when excessive for the child's age.
  • what characterizes ADHD is the intensity,persistence, and patterning of the behaviours which significantly impairs social, academic, and work activities.

Behaviours Associated with ADHD

1. Inattention:

  • often fails to give close attention to details; makes careless mistakes in schoolwork and other activities
  • often has difficulty sustaining attention in tasks or play activities
  • often does not seem to listen when spoken to directly
  • often does not follow through on instructions and fails to finish schoolwork, chores, or other duties
  • often has difficulty organizing tasks and activities
  • often avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (such as schoolwork or homework)
  • often loses things necessary for tasks or activities (e.g. toys, school assignments, pencil, books, or tools)
  • often easily distracted by extraneous stimuli
  • often forgetful in daily activities

2. Impulsivity:

  • often blurts out answers before questions have been completed
  • often has difficulty awaiting turn
  • often interrupts or intrudes on others

3. Hyperactivity:

  • often fidgets with hands or feet or squirms in seat
  • often leaves seat in the classroom or wherever remaining seated is expected
  • often runs about or climbs excessively in situations where it is inappropriate
  • often has difficulty playing or engaging in leisure activities quietly
  • often "on the go" or often acts as if "driven by a motor"
  • often talks excessively

Who can diagnose ADHD?

Psychologists, psychological associates (with access to diagnosis) and physicians properly diagnose ADHD using criteria from the three characteristics of inattention, impulsivity and hyperactivity. A child must show a significant number of the characteristic behaviours more frequently than expected for a child that age, in at least two different environments, and for at least six consecutive months. Onset of these behaviours should be before the age of seven. Since a child may show difficulties with sustaining attention for a variety of reasons, psychologists diagnosing ADHD will use a multidisciplinary approach involving parents, classroom teachers and other individuals who know the child.

How is ADHD best treated?

There is no single effective method for treating ADHD. Research in modifying children's environments; counselling; behaviour modification; medication and individualized academic programing all have shown promise. No one technique, nor single combination of techniques is effective with all children. In particular, treating ADHD with stimulant medication remains inconclusive. There is little evidence that academic achievement improves with the use of medications such as Ritalin, Dexedrine and Cylert alone. Medication can and does increase the attention span of children. However, it is unclear that thinking, memory and academic skills are improved by simply helping children to attend and engage in learning activities for longer periods of time. Similarly, other treatment approaches to ADHD which emphasize specific diets, megavitamins, restrictions on food dyes and listening stimulation, have not been shown to have a significant effect on ADHD in well controlled research studies.

In the midst of all the uncertainty as to how to deal effectively with ADHD children, it appears that an eclectic or broad-based approach is best. A combination of behaviour modification, medication, and classroom and home management techniques has shown the most promising results. Only an individualized approach implemented by parents and teachers, under the direction and supervision of psychologists and physicians, will meet the special needs of children with ADHD.

Helpful Tips:

  1. only experienced psychologists and physicians can accurately diagnose ADHD.
  2. parents should be cautious not to diagnose their children after reading the characteristic behaviours of ADHD (be aware and concerned, but don't diagnose).
  3. seek advice from an experienced psychologist or physician for an accurate diagnosis and appropriate treatment plan.
  4. all methods of treatment should be closely monitored; be wary of the "take these pills and see me in six months" approach.

Facts and Figures about ADHD

  • According to the National Institutes of Mental Health (NIMH), "ADHD (Attention Deficit Hyperactivity Disorder) refers to a family of related chronic neurobiological disorders that interfere with the individual's capacity to regulate activity level (hyperactivity), inhibit behaviour (impulsivity), and attend to tasks (inattention) in developmentally appropriate ways."
  • ADHD, under different labels, has been recognized as a disorder from at least the 1940's. Far from being an "invented disease", it is well substantiated that ADHD is a disorder which involves a dysfunction in the prefrontal cortex of the brain. This is the area of the brain which is involved in higher-order planning skills, and which permits us to inhibit responding. Using sophisticated neural imaging techniques, it has been discovered that there are structural differences in the brains of individuals with ADHD. The parts of the brain responsible for controlling attention have been found to use less glucose (a major fuel source) in ADHD individuals compared to nonaffected individuals. In addition, evidence strongly suggests that ADHD individuals also demonstrate neurochemical differences, in particular less of a chemical neurotransmitter called dopamine which is needed in some areas of the brain to focus attention and to control impulsive responding.
  • There is very strong evidence of a genetic component in this disorder, again refuting suggestions that the condition is not real. At least 1/3 of fathers who were diagnosed as having ADHD as children have children who are also diagnosed with ADHD. Siblings of ADHD children are 5 to 7 times more likely to demonstrate the disorder than are children from unaffected families. Even more compelling, the majority of identical twins share the trait.
  • Nongenetic causes account for about 20 to 30 percent of ADHD cases, and include fetal distress, premature birth, maternal alcohol use during pregnancy, exposure to high levels of lead during early childhood, traumatic brain injury (especially injury of the frontal lobes) and sleep problems. There is no evidence that ADHD is caused by food allergies, by watching too much TV, by excess sugar, by poor home life, or by poor schooling.
  • Current data from the U.S. National Institutes of Mental Health (NIMH) estimate that about 5 to 6 percent of school age boys in the U.S. are diagnosed with this disorder. Boys with the disorder outnumber girls by a factor of 2 or 3. This translates into about 2 million children in the U.S. Similar percentages are reported for Canadian children.
  • There is no independent test for ADHD. This is a situation common to most psychiatric disorders, including schizophrenia and autism, due to their complexity and variability. Primary care and developmental pediatricians, family practitioners, child neurologists, psychologists and psychiatrists are the providers responsible for assessment, diagnosis and treatment of most children with ADHD. NIMH data indicate that family doctors diagnose more quickly and prescribe medication more frequently than psychiatrists and pediatricians. Misdiagnosis can occur, as other disorders (learning disabilities, chronic ear infections, language delays, adjustment problems, substance abuse, personality disorders, epilepsy) can produce similar symptoms. 
    In addition, a number of other disorders often accompany ADHD, including learning disabilities, fetal alcohol syndrome or effects, developmental delays, language disorders, anxiety disorders, mood disorders, conduct disorders and tic disorders, including Tourette's syndrome. The more carefully the assessment is conducted, and the more information considered (e.g., medical, developmental, school, psychosocial and family histories, parent and teacher ratings, psychological testing) the lower the incidence is found to be for this disorder. Diagnosis should be based upon a thorough investigation of the child's life, in and outside of the home.
  • Many children do not "outgrow" ADHD: about 1/3 of individuals diagnosed as children still meet the formal criteria as adults. Hyperactive-impulsive symptoms generally decrease with age, but symptoms of inattention do not.
  • Without treatment, ADHD children are at significantly higher risk for a variety of negative life outcomes. They are more likely to be involved in accidents, especially motor vehicle accidents during adolescence, as well as tobacco use, early pregnancy and lower educational attainment. Almost half of ADHD children (mostly boys) exhibit symptoms of Oppositional Defiant Disorder, including stubbornness, bursts of temper, belligerent and defiant behaviour. In some of these children, there is a progression into the much more serious behavioural problems associated with a diagnosis of Conduct Disorder. About 25 percent of these children experience anxiety or depression. Some develop antisocial personality disorder.
  • There are three types of stimulant most commonly prescribed for this disorder, and Ritalin has proved to be the most effective. Its clinical effects peak about one hour after each dose, and dissipate in about 4 hours. Ritalin appears to act by increasing the amount of dopamine at the synapses, addressing the deficiency which may underlie this disorder. Nine out of ten children with ADHD improve with the use of one of the three stimulant medications.
  • Ritalin has been prescribed for children since the 1970's and consequently has been well studied. Side effects do include sleep problems, appetite loss and, in rare cases, facial tics. There may be a negative effect on growth rate, although ultimate height does not appear to be affected. Interestingly, the NIMH study found that the highest level of side-effects was reported for children receiving the placebo ("sugar pill") rather than the actual stimulant medication. Ritalin can be addictive when abused by adolescents and adults. However, long-term tolerance is rare as there is no need to increase the dosage to maintain clinical effects. Contrary to concerns about potential drug abuse, ADHD boys treated with stimulants are significantly less likely to abuse drugs and alcohol when older.
  • The NIMH and the US Department of Education recently published the results of the most comprehensive study of treatment effectiveness for ADHD ever undertaken. The Multimodal Treatment Study of Children with ADHD cost $11 million (US), and conclusively demonstrated that long-term combinations of psychosocial and stimulant treatments, as well as thorough and well-monitored medical management alone, were both significantly superior to intensive behavioural treatments alone and to treatments offered by most medical practitioners in the community. Stimulants were found to have 3-fold greater benefit on behaviour ratings than on ratings of attention, and the best effect on academics and social behaviour were observed when medication was maintained for a year or more. In contrast, behavioural parent training and behavioural interventions in the classroom setting had limited effects on hyperactivity, but large effects in reducing oppositionality, defiance and aggression.
  • American statistics indicate that production of Ritalin has increased about 500 percent since 1990. Health Canada estimates that prescriptions for Ritalin have increased 637 percent over the same period. Current estimates place the number of Canadian children taking Ritalin at about 2 to 3 percent, which represents at most 145,000 children in the country. No one denies that misuse and abuse of this drug occur. However, authorities agree that the increase in prescriptions primarily represents the fact that children with the inattentive type of this disorder (predominantly girls) are now being identified in addition to children with either the hyperactive-impulsive type and combined type, that children are being diagnosed earlier, and that they are staying on the drug for longer periods of time (often throughout adolescence and into adulthood).
  • There are a number of treatments for ADHD which have no proven effectiveness: allergy treatments, megavitamins, chiropractic adjustment, treatment for yeast infection, eye training, or the use of specially coloured glasses. Restricted diets have been found in some studies to only help about 5 percent of children with ADHD, primarily younger children or those with food allergies. Both Efalex and pycnogenol have no scientifically documented effectiveness in helping children with ADHD, and their manufacturers have been recently prohibited from making any such claims by unanimous decisions of the US Federal Trade Commission. For parents, the message should be clear: it does not help to delay effective treatment while trying out unknown or unproven ones.
  • Families with ADHD kids have greater parental frustration, marital discord and rates of divorce. 
    It is very hard to parent a child who is full of uncontrolled energy, who constantly leaves messes, throws tantrums and doesn't listen or follow instructions at a level appropriate for his/her age. If children do not develop age-appropriate attention and inhibitory control, they continue to encounter the same problems and to respond in the same ineffective ways, even though they may know better and try very hard to change. 
    Discipline (reasoning, scolding and especially hitting) doesn't work, as the children are not choosing to act in these negative ways. Children exposed to such an approach quickly label themselves as "bad", and come to experience scolding as virtually the only kind of attention that they get. As a result, they develop a cycle of frustration, blame and anger with their parents. 
    In addition, research has demonstrated that children imitate or model such aggressive behaviour from their parents, and are more likely to try it with other children. 
    In fact, recent data from the Canadian National Longitudinal Study of Children and Youth have indicated that children who experience hostile or ineffective parenting are nine times more likely to demonstrate behaviour problems than are children exposed to positive parenting approaches. The best approach consists of positive, consistent parenting, modest goals and flexible structure.
  • The poor prognosis for children with this disorder who fail to receive effective treatment underscores the importance of early identification and intervention for children with ADHD. The complex of hyperactivity, impulsivity and attentional problems is frequently observable in children as early as the preschool years. This combination of difficulties is strongly predictive of later behaviour problems. However, inattention and impulsivity can follow from many kinds of problems at this age (e.g., language delays, recurrent ear infections), as well as from other sources such as natural rambunctiousness, or stressors such as divorce, neglect or inadequate child care. Consequently, diagnosis of ADHD in preschoolers should only be made cautiously by experts well trained in child neurobiological disorders. Medication for this very young age group is generally not recommended, as results of such treatment have not been thoroughly evaluated for effectiveness or safety. The NIMH study recommends that treatment should focus on structured play school, along with parent training and support.
  • Aggressive and anti-social behaviour has been found to consolidate between the ages of 6 and 10, suggesting that this age group is a particularly important one to screen for children with this disorder. Information should be collected from both parents and teachers, and ideally a multi-disciplinary approach should be implemented, involving both health-related and school-based assessments. Unfortunately, because of different legislative and funding structures, there is currently a "disconnect" between assessments conducted in these different settings.
  • In spite of its demonstrated effectiveness, medication alone is not necessarily the best treatment for all children. Treatment decisions should be based upon each child's individual needs, personal and medical history, research findings, and other relevant factors. Treatment combining medical management with behavioural approaches is more effective in addressing issues such as anxiety, academic performance, oppositionality, parent-child relationships and social skills. Children receiving combined treatments tend to require about 20 percent less medication.

Psychological Services provided by Boards of Education can help!

It is important to point out that where initial strategies at home and program modifications at school have not been successful, assistance from Psychological Services are available through your Board of Education to assist with these situations.

Psychological Services of the Toronto District School Board has developed a Psychological Assessment Checklist for ADHD (pdf) outlining best practice for the assessment and diagnosis of this condition.


On November 27, 2003, the Community Health Systems Resource Group at the Hospital for Sick Children, supported by sponsorship from Shire Biochem Inc. and the Learning Disabilities Association of Ontario, presented a conference on AD/HD to discuss recent research into causes, processing deficits and educational interventions. Presenters were Russell Schachar, M.D., F.R.C.P.(C), Senior Scientist, HSC Research Institute, Professor of Psychiatry, University of Toronto, and Rosemary Tannock, Ph.D.,Senior Scientist, Brain &; Behavior Program, HSC, Associate Professor of Psychiatry, University of Toronto. The presenters have generously offered to have their PowerPoint prese ntations posted as links from this webpage:

Dr. Russell Schachar's presentation (minus copyrighted images):

Clinical and Neurological Perspectives of ADHD (411 kb)

Dr. Rosemary Tannock's presentations:

Re-Conceptualizing ADHD (PowerPoint, 353 kb)

ADHD and The Classroom (2.13 Mb)

Due to their size, these links (especially the last one) may take some time to load at slower connection speeds. If the document does not open in your browser, right click on the link and choose "Save Target As" and save the document to your computer. You can then open it in PowerPoint. If you do not have PowerPoint on your computer, you can download PowerPoint 2003 Viewer (1911 kb) for free at the Microsoft site. This program will allow you to view these presentations.

The Association would like to thank the presenters and Peter Chaban, Education Projects Co-ordinator at HSC, for making this material available on our site.

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