How many people have ADHD, and why is it becoming so common?
Another area of ongoing debate surrounds the question, "How many people have ADHD?" The frequency of a disease or disorder is called a prevalence rate. Prevalence rates for ADHD appear to be sharply rising. In the United States, from 1997 to 2006, the rate of ADHD diagnoses went up an average of 3% per year. The percentage of children diagnosed with ADHD continued to increase from 7.8% in 2003; to 9.5% in 2007; to 11.0% in 2011. That's a 44% increase in 4 years! The number is even higher according to parental reports: In the USA, 6.4 million children (ages 4-17), or 11%, have had an ADHD diagnosis. Of this group, 69% are taking medications for the condition (National Survey of Children's Health, 2011).
Although there can be error in statistical analysis, error alone cannot account for this increase. The likelihood of error is offset by improvements in data collection methods. As causes for possible error have been identified, methods to correct these errors have been developed. Therefore, by numbers, there really isn't any debate that the numbers are increasing. What experts continue to debate are the causes for such increases.
Moreover, despite drastic increases, many experts believe the statistics actually underestimate the accurate number people with ADHD (prevalence). These professionals think there are many people with ADHD who have not yet been evaluated or diagnosed.
Another factor affecting prevalence rates involves the use of diagnostic labels in children. Some people are reluctant to label children as mentally ill. This is particularly true if it leads to giving them medication. This understandable type of stigma-avoidance could cause a decrease the number of children referred for evaluation. This reluctance to refer children for evaluation would lead to an underestimation of ADHD prevalence.
Alternatively, another group of professionals believe the current prevalence rates of ADHD diagnoses are overestimated. They cite errors in diagnosis and assessment of symptoms as one plausible cause. The diagnostic criteria for ADHD are fairly general. Therefore, it is possible that various types of disruptive behavior, and/or learning disabilities, are mislabeled as ADHD. In addition, there is no objective, standardized ADHD assessment tool that measures all of the symptoms listed in the DSM-5. Instead, the primary methods used to assess ADHD are self-report; parent and teacher questionnaires; or clinician-rated behavioral observations. These types of assessment tools are somewhat subjective. As a result, they can be influenced by feelings, values, cultural norms, and opinions.
In some cases, people who provide self-reports or behavioral observations may be unduly influenced by the idea that ADHD is increasingly common. They may be more willing to endorse symptoms that reflect this diagnosis. This suggests a reduced stigma associated with the disorder. From this perspective, the net effect would be to overestimate ADHD. Of course, an alternative explanation is also valid. The vague and general diagnostic description of symptoms, and the subjectivity of the assessment tools, could just as easily lead to an underestimate of ADHD. This would occur if people are misdiagnosed with other disorders that have shared symptoms; or, while trying to avoid the perceived stigma of this label. For the reasons cited above, the Center for Disease Control (CDC) emphasizes that statements about rates of the disorder are premature (Center for Disease Control, 2009).
Other researchers speculate that the increase in prevalence does not reflect a true increase. This argument proposes that the demands of the modern world simply make ADHD symptoms more obvious. From this perspective the prevalence itself is not increasing: We are just better able to detect it. To illustrate, our world is filled with electronic gadgets. This includes computers and cell phones that require more focused attention and concentration than was needed in the past. Thus, the change in the environment upped the demand for heightened attention. This in turn led to more people becoming dysfunctional in our modern environment. This interesting speculation recognizes that the survival skills needed in ancient civilizations (e.g., hunter-gatherer societies) are quite different than skills needed in today's world. In fact, ADHD characteristics could be desirable qualities that enhanced the chance of survival in pre-historic times. Viewed from this perspective, ADHD is just as prevalent as it was in the past. What has changed are the environmental demands. Therefore, what was once a beneficial skill is now a harmful symptom, leading to daily difficulties with everyday functioning.
In a related manner, cultures evolve and change; sometimes not for the best. Some researchers argue the ADHD increase is in response to contemporary lifestyle changes. These modern lifestyle changes include decreased physical activity; unstructured play time; and time spent in a natural environment. This approach suggests that as we move further away from our natural environment, and become detached from the nature's rhythm, we develop impulsivity, restlessness, and hyperactivity. This theory is similar to the ancient survival skill set argument described above. Both arguments suggest ADHD is on the rise because the symptoms became problematic when modern societies became disconnected from nature.
Whatever the reason, rates of newly diagnosed cases of ADHD are on the rise. The reason for this increase remains unresolved. While the cause and accuracy of these increases remains under debate, the increasing rates are still a reason for concern.