Are the youngest children in the classroom diagnosed with ADHD more often? According to a study completed by the University of British Columbia, the answer is YES. This study reviewed information on almost one million school age children, where the cutoff date for entering school is December. Results from the study showed that children born in December, or the youngest in the classroom, were 39 percent more likely to be diagnosed with ADHD and 48 percent more likely to be treated with medication.
Dr. Ari Tuckman, a psychologist specializing in treating ADHD and the previous vice-president of the Attention Deficit Disorder Association, believes the findings make sense. Because children can be a full year younger than some of their classmates, differences in the maturity level and academic abilities may be very apparent, especially in the younger grades. Tuckman states, "A diagnosis of ADHD is made by comparing someone to peers of the same age. Unfortunately, when kids in the same class can differ in age by almost a full year, that can be a big difference, especially in elementary school. There's a much bigger difference between six and seven than 16 and 17. So in these cases, the comparison group (for example, other second graders in this child's class) are not really the best comparison group." 
Richard Morrow, the study's lead researcher, believes that "a lack of maturity is being misinterpreted as symptoms of ADHD."  Morrow also points to two recent studies in the U.S. that indicated both date of birth and age at the start of school were predictors of diagnosis and treatment of ADHD. He began his study to find out if the same was true in Canada.
The study recommends that doctors, before making a diagnosis of ADHD, compare the child's age to his or her classmates when assessing school performance as well as look at the child's behavior in other settings. According to the Diagnostic and Statistical Manual, a diagnosis of ADHD should occur only if "Some impairment from the symptoms is present in two or more settings (e.g. at school/work and at home)."  Dr Tuckman agrees, explaining that this study "points out the importance of a full diagnostic evaluation that doesn't just look at school performance, but also looks at how this child functions at home, with friends and in extracurricular activities." 
Because there is no laboratory test that can prove, or disprove, the presence of ADHD, the diagnosis is based on behavioral and intellectual analysis (ADHD does not impact intellectual abilities but performing below where intellectual abilities indicate can be a symptom of ADHD). Rather than using grade levels as a comparison point, it would make more sense to compare with children of the same age.
What do you think? Is your child, or a child you know, one of the youngest in the class? Do you think their maturity level, as a younger child, was taken into consideration during the assessment?