Thu Jun 29

You might have heard ADHD risks being over-diagnosed. Here's why that's not the case

Written by: Christopher Gyngell, Research Fellow in Biomedical Ethics, The University of Melbourne

At the same time as it has attracted support and understanding, attention deficit hyperactivity disorder (ADHD) has invoked passionate debate in recent years. One hot topic is whether ADHD is being over-diagnosed.

This concern dovetails with calls from GPs ^[1] to be able to help provide wider access to diagnosis and for the condition to be added ^[2] to the National Disability Insurance Scheme (NDIS).

Public hearings for the Australian Senate’s inquiry ^[3] into “consistent, timely and best practice assessment” of ADHD and support services begin today.

Reflecting on the unique features of ADHD, as well as how the idea of overdiagnosis came about, shows this misplaced concern should not distract us from helping people impacted by the condition.

What is ADHD?

ADHD is a neurodevelopmental condition that involves a person’s ability to regulate their behaviour, attention, and/or activity levels. Worldwide, around 5% of children and 2.5% of adults ^[5] meet the full diagnostic criteria ^[6] for ADHD.

Importantly, just having hyperactive, impulsive and inattentive symptoms is not sufficient to qualify for a diagnosis of ADHD. To meet current diagnostic criteria ^[7], these symptoms must have a negative effect on a person’s “social, school, or work functioning”.

This makes ADHD (and other mental health conditions) different from most physical health problems like cancer, diabetes, or heart disease. You can have cancer without it affecting your family, work, or social life. Some people might have cancer but not show any symptoms and still be doing well.

But by definition, you can’t have ADHD without both showing its symptoms and feeling their impact.

Overdiagnosis or misdiagnosis?

Overdiagnosis is a concept first developed in cancer ^[9] screening to highlight situations where ^[10] “the diagnosis of disease that would never cause symptoms or death during a given patient’s lifetime”. This definition has since been employed in many other areas of medicine, as well as analyses of health systems.

When defined in this way, overdiagnosis is distinct ^[11] from the concept of misdiagnosis, which is where an incorrect diagnosis has been made. Misdiagnosis is when someone is diagnosed with a condition when they do not meet diagnostic criteria.

Overdiagnosis is something we should avoid. If a condition is not going to cause a person harm, we should not waste medical resources identifying it, or use invasive procedures to treat it. But when we reflect on the fact it’s impossible to have ADHD and not experience negative effects, we can see ADHD is not a condition that can be over-diagnosed in the way a disease such as cancer can.

Different definitions

Of course, there are other ways we could define overdiagnosis, so that it could apply to ADHD.

One 2021 article ^[13] on ADHD and overdiagnosis defined it as occurring when the “net effect of the diagnosis is unfavourable”. But the implications of this definition of overdiagnosis are difficult to unpack.

There are many reasons an ADHD diagnosis may be “unfavourable”, for some individuals. It could be a misdiagnosis. A person might not have access to any needed treatments and/or social supports. Some people experience negative side effects from ADHD treatments, or experience stigma ^[14] as a result of ADHD diagnosis.

One finding sometimes quoted as evidence ^[15] for overdiagnosis of ADHD is that children who are youngest in their class are the ones most likely to be diagnosed.

But when you think about ADHD as not just having certain symptoms, but as having harmful outcomes, this might be expected. Trouble staying focused during class is more likely to be harmful if you are already behind your classmates – so harms are compounded.

In contrast to over-diagnosed physical diseases, it will still be important to identify such children, to reduce the negative impact of their inattentiveness. This need not involve medications but could involve environmental interventions – including perhaps repeating a year of school.

Not a medical condition

Some concerns about ADHD overdiagnosis appear to be based on a belief ADHD should not ^[17] be considered as a medical condition. From this perspective, the concerns would again be more accurately and transparently phrased in terms of misdiagnosis.

It is true some children who currently have an ADHD diagnosis might in fact be hyperactive, impulsive, or inattentive, but these traits may have neutral or positive effects on their lives. Again, this would not be an overdiagnosis, but an incorrect diagnosis.

Even in the United States where rates of ADHD diagnosis exceed 5%^[18], they still fall short of the estimated epidemiological prevalence ^[19]. That means even though there have been significant increases ^[20] in the rates of diagnosis of ADHD over recent years, there are still many more children, adolescents and adults who likely meet the diagnostic criteria for ADHD. They may never have had these problems recognised, do not have a diagnosis and do not get any support.

Where to from here?

So GPs and others – like Mental Health Nurse Practitioners ^[21] – may well play an important role in assessing and managing ADHD.

There would clearly need to be extensive training and support and also changes in the way assessments are funded. A good assessment takes time and at the moment funding preferences shorter appointments.

As things stand, we are a long way from “overdiagnosis”. In fact, we are still a long way from adequately supporting those who need it.