Hyperactivity

Topic Editor: Russell Schachar, MD, University of Toronto, Canada

Attention-Deficit/Hyperactivity disorder (ADHD) is a neuropsychiatric disorder defined by developmentally atypical, persistent and impairing restlessness, impulsiveness and inattentiveness starting from an early age. ADHD can be broken down into three subtypes based on the type of behaviours that are most prominent: 1) the inattentive type; 2) the hyperactive-impulsive type; and 3) the combined type depending on the nature of the symptoms. The disorder is diagnosed when the child’s symptoms are present and impairing in more than one context such as in school, at home or outside of the home. ADHD is estimated to affect 3 to 7% of school-age children worldwide, and boys show higher rates of ADHD than girls. ADHD tends to co-occur with other psychiatric or developmental disorders (e.g., anxiety, mood disorder, learning or language disabilities, conduct disorder and sleep difficulties) in 50 to 66% of cases. ADHD persists into adulthood in more than half of affected individuals. ADHD symptoms and its concurrent disorders interfere with academic and behavioural functioning at school and so children have lower rates of high school completion. They are also more likely to experience employment difficulties as they grow older. Other negative consequences relating to ADHD include difficult interpersonal relationships and higher prevalence of accidental injuries, driving accidents and teen pregnancy. In sum, ADHD represents an important public health concern and may engender high personal and societal costs.

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