This post is my paraphrase from an article written by Maggie Koerth-Baker entitled, "The Not So Hidden Cause Behind the ADHD Epidemic" (2013).
Even before I start, let me be clear and say that the mental health field is not able to provide absolute causality, but we are able to provide correlations. This means that what I am able to present is not the definitive reason for our increase of ADHD diagnosis, but these may be related variables.
1. Evidence suggests that ADHD has a biological basis and is genetically inheritable.
Twin studies suggest that ADHD has a genetic basis. Identical twins have been found to be more likely to share it than fraternal twins. Brain-imaging studies have shown distinct differences between the brains of people who have been diagnosed with ADHD compared to those who have not.
2. Diagnostic approach.
There is no conclusive test to diagnose ADHD. Most children are diagnosed with ADHD from an appointment with their pediatrician. The diagnosis can be as simple as prescribing an ADHD medication (a stimulant) to a child and seeing if it helps improve their school performance. If their child has improved performance, then it confirms their ADHD diagnosis.
3. ADHD is included under the Individuals With Disabilities Education Act in 1991.
The diagnosis of ADHD provides access to academic accommodations such as tutoring, individualized education, and time allowances on assignments and standardized tests.
4. Changes in the Food and Drug Administration in 1997 allowed drug companies to market directly to the public.
By the late 1990s, there was more awareness of the ADHD diagnosis, its symptoms, and that there were drugs to treat it.
5. The educational policy, No Child Left Behind Act in 2002, was the first federal policy to link school financing to standardized-test performance.
The correlations between the implementation of these policies and the rates of ADHD diagnosis matched on a regional scale. When a state passed policies to reward schools for their standardized-test scores, ADHD diagnoses in that state would increase soon afterward.
6. Diagnostic criteria.
In the U.S., our diagnosis of ADHD is defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM). Europeans have historically used the International Classification of Diseases (ICD) for diagnosing. The ICD has much stricter guidelines for ADHD diagnosis, but the DSM has become more widely used in more places.
7. The shift from a moral framework to the medical model.
Our current society is increasingly valuing non-judgmental acceptance, not wanting to impose our morals on one another. Schools used to punish kids who wouldn’t sit still. Today we tend to see those kids as needing therapy and medicine.
8. Expectations for children has changed.
In the past 30 years as ADHD diagnoses have increased, the American childhood experience has drastically changed. Even at the grade-school level, kids now have more homework, less recess, and a lot less unstructured free time to play. There are many reasons for this shift in childhood, but social-economic dynamics have been a driving force. ADHD has become a convenient social catchall for what happens when kids are being kids when we expect them to be adults.
9. Devices and ADHD.
This is not discussed in Koerth-Baker's article, but there are strong parallels between the use of devices and the increase of ADHD diagnoses so I decided to add this point here. There is evidence that the use of the operational conditioning concept of intermittent reward reinforcement schedule is related to the brain reward system: dopamine hits.
10. Increased awareness of ADHD.
In the early 1900's, ADHD was called "Hyperkinetic reaction of childhood". The stimulant, methylphenidate, was first made in 1944 and marketed as Ritalin in 1954 to treat ADHD. In 1980, the DSM changed the name to Attention Deficit Disorder (ADD). The name changed to ADHD in 1987. Our awareness and understanding of ADHD has grown which may also contribute to its increased diagnosis.