'A risk of over-diagnosing ADHD', leading NZ psychiatrist warns

In the latest episode of RNZ's unedited interview series, 30 with Guyon Espiner, Guyon sits down with leading addiction psychiatrist Dr Sam McBride, who raises concerns around the potential over-diagnosis of attention deficit hyper-activity disorder, or ADHD - four letters that lately seem to be on everyone's mind.

ADHD is a condition that affects a person's ability to focus, control impulses and regulate activity levels, and it can impact daily functioning and quality of life.

In recent years, ADHD diagnoses and prescriptions have surged around the world, particularly in wealthier societies.

In New Zealand, prescriptions for ADHD medication have jumped tenfold since 2006. In the past two years Pharmac reported a 140 percent rise in demand for these medications.

Sam McBride, the New Zealand representative on the Faculty of Addiction Psychiatry at the Royal Australian and New Zealand College of Psychiatrists believes the trend is not simply down to growing awareness.

"I think we are over-prescribing, and there is a risk of over-diagnosing ADHD," he says.

He points to international trends as a warning sign, noting that the prevalence of ADHD varies significantly between countries.

International estimates suggest that around 5 percent of children and adolescents, and 2.5 percent of adults, would meet the diagnostic criteria for ADHD.

In the US, up to 10 percent of children have been diagnosed, McBride says.

"[That] suggests that there's a real potential for over-diagnosis. And I am concerned that we might be moving into that territory in New Zealand."

He says a clinical diagnosis of ADHD in New Zealand typically involves multiple appointments and may include observational visits to a child's school, for instance.

However, the threshold for a diagnosis has "loosened" over time, he says.

He worries that the increase in diagnoses may be a symptom of oversimplifying complex problems.

"We might be missing other conditions that could be associated with symptoms of inattention, and we're not talking about environmental factors that might be associated with it as well," McBride says.

ADHD has evoked strong reactions from professionals and the general public, with competing arguments that ADHD is either underdiagnosed or overdiagnosed.

Earlier this year, some New Zealand researchers said there was a treatment gap.

McBride acknowledges the topic is divisive, but says his views are supported by others in the profession.

"In any field there's a range of views. [But] I was reassured when preparing for this interview and talking to peers - not just people I know - to child and adolescent psychiatrists and other other psychiatrists. There is a lot of concern out there."

While McBride warns of the risk of overdiagnosis, he says the disorder can have a functionally debilitating effect on those at the severe end of the spectrum.

"It's important not to downplay ADHD and the impact that it can have. It's associated with high rates of imprisonment, it's associated with impaired academic performance; it's associated with impaired social relationships, and because of that, people can feel bad about themselves and experience other associated problems."

"I work in addiction service. [ADHD is] highly represented within addiction services. And so, I diagnose and treat ADHD within our service. And it can be highly rewarding when you get it right."

He says there is a broader issue in both psychiatry and popular culture of "concept creep," where terms like 'depression,' 'trauma' and 'anxiety' are used too loosely, or applied too liberally.

"Anxiety, in of itself, is a normal experience. It's a really useful experience. It prepares us for potential threats or something we need to get ready for, like exams. But [being anxious] isn't an anxiety disorder, which is associated with significant impairment," McBride says.

He makes a similar case for ADHD. "We could run the risk of pathologising normal behaviour."

* 30 with Guyon Espiner comes out every week on RNZ, Youtube, TVNZ+ and wherever you get your podcasts.

Pharmaceutical companies and self-diagnosis

McBride also highlights the role that pharmaceutical companies play in influencing the current environment.

"I think we need to be really cautious about our relationship with pharmaceutical companies," he says. "It's clearly shown through research that by engaging with pharmaceutical companies, our practice changes, and we will be more likely to prescribe the medications that they have."

McBride says New Zealand is better in this regard compared to other countries, but the relationship between the psychiatric community and pharmaceutical market interests still requires vigilance.

"It's a dynamic we need to be really, really cautious and careful about," he says.

That can be exacerbated by the promotion of ADHD through social media and pharmaceutical-sponsored websites, McBride says.

"They have websites developed to provide information on ADHD that they sponsor. So that's really obvious."

He is also critical of publicly available clinical questionnaires that can be used by anyone to "self-diagnose" online.

"Screening tests, in of themselves, aren't worth much," says McBride. "Diagnosis takes time. It's not a snapshot, and it shouldn't be a single interview or interaction.

"Personally, I don't think they should be available in the public domain, because they require some recognition of the limitations of those tests in the context. They don't contextualise the symptoms that that person has within any environment that they're in, or with what else might be going on."

McBride points out that the tests are designed to reduce the rate of false negatives within a clinical diagnosis by casting a wide net, but this approach carries risks.

"They have a risk of reinforcing the diagnosis in a person's mind. We all have a cognitive bias. We look out for what we believe, and when we're primed with this information, we're often more likely to see it in ourselves," he says.

Are we over-medicating?

As well as a risk of overdiagnosis, McBride says over-medication is already a problem, especially for those with milder symptoms.

"We tend to overestimate the benefits of medication. We mistake subjective improvement - this medication makes me feel better - versus functional change over time," he says.

"If we look at the evidence for use of medications, and it's predominantly short-term, the evidence is often poor. It's often been influenced by pharmaceutical companies or there are research flaws in terms of how it's developed.

"The most robust kind of evidence is that actually, the gains from medication are limited, in that they don't necessarily seem to be sustained over long periods of time."

Medication should be prioritised for those with severe ADHD symptoms, versus what he views as a "one size fits all" approach, where medication is promoted as the primary intervention.

"I think people at the severe end of ADHD are the ones who should be prioritised; they're the people who are most likely to benefit, and where benefits are more likely to outweigh risks," he says.

"I'm concerned that we are simplifying a complex diagnosis, we are simplifying treatments for that diagnosis, and yes, that we run the risk of over-medicating."

There are other options available, he says.

"What we're not hearing about is psychological advanced therapies, for example, or environmental strategies that people could implement."