Diagnosing ADHD: why is it so challenging?

From ABC Health and Wellbeing, 7 March 2014:

Toddlers are hard work. As any parent knows, they’re into everything, they have the attention span of a goldfish, the focus of a spinning disco ball, and the exploratory instincts of a spaniel puppy.

That’s all well and good when they’re toddlers, but what happens when those traits persist into early childhood, teenage years and even adulthood?

This is Attention Deficit Hyperactivity Disorder, or ADHD and it’s one of the most controversial diagnoses to hit the headlines in recent years, largely because it touches a raw nerve in society about how we expect children to behave, and who is to blame when they don’t.

Further complicating the issue is the fact that the most common treatment for ADHD is medication, which can be effective, though not always, and can have serious side effects.

An umbrella term

ADHD is not a disease like cancer or diabetes that is either there or not there. It’s an umbrella term applied to a range of behaviours that affect a child’s ability to function and which may have a number of root causes, says paediatrician Dr Daryl Efron.

“When children are referred to paediatricians with difficulties – which might be learning, social, or behavioural – our job is to try to understand the contributing factors behind that and usually there’s more than one set of contributing factors,’ says Efron, a consultant paediatrician at Melbourne’s Royal Children’s Hospital.

“We think of the contributing factors in sets so one set might be what we call the ADHD symptoms, another set might be emotional things, such as anxiety or self-esteem, another set may be cognitive, such as learning difficulties, another set might be social, difficulties at home or bullying or so on.”

Varying figures

It’s difficult to get a clear sense of how common ADHD is; the incidence varies so wildly between countries and even between states. While it’s generally accepted that between 5 to 7 per cent of children have ADHD, psychologist Dr Rae Thomas says one recent review found rates range from 1.7 to 20 per cent.

“The reason is that different countries use different systems to classify,” says Thomas, senior research fellow at the Center for Research in Evidence-Based Practice at Bond University.

But even in countries that have a standard system for diagnosing ADHD, such as the US which uses the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), there is still significant variation in diagnosis rates from one part of the country to another.

Thomas suggests a number of factors could be to blame for this variation in diagnosis rates, even when the same diagnostic guidelines are being used.

One of these is the fact that some children are being labelled as ‘mild’ or ‘moderate’ ADHD, when in fact no such categories exist.

“The CDC [Centres for Disease Control] data from US, who talk about wide variance prevalence rates, 85 per cent of children with ADHD in their report from 2010 are diagnosed as mild to moderate, and there’s your problem – there’s no definition of mild or moderate or severe ADHD,” says Thomas.

‘For kids who have ADHD in its proper sense, I don’t even want to call these kids severe – I want to call them ADHD,” she says. ‘As far as I’m concerned, severe should be the only ADHD.”

“We need to save this diagnosis for these kids who really need it so that they won’t be stigmatised,” she says. “A while ago, Asperger’s [syndrome] was in the same boat as ADHD – I have seen kids with true Asperger’s and I have seen kids who are just really socially awkward – and we need to be careful with our diagnosis so we don’t hurt the ones who need it.”

The problem with this apparent stretching of the diagnostic boundaries is that it is driving up prevalence rates, and that in turn can start a positive feedback loop whereby the more common a condition is, the more people turn to it as an explanation.

“We already know that those [mild and moderate ADHD] children are driving these high prevalence rates [and] my concern is that prevalence rates have an anchoring effect,” she says.

“That means that when people hear that it is rare, people don’t go hunting for it but when when people hear that a prevalence rates is high, ‘gosh, so many kids have this’, clinicians go hunting for it.”

How the diagnosis is made?

According to the DSM-5 – which is generally viewed as psychiatry’s ‘bible’ – for a diagnosis of ADHD, “children must have at least six symptoms from either (or both) the inattention group of criteria and the hyperactivity and impulsivity criteria.”

The DSM-5 criteria include a range of behaviours such as difficulty sustaining attention in tasks or play activities, being fidgety, not listening when spoken to directly, not following through on instructions, and easily distracted by external stimuli. (For more information on symptoms see the ADHD fact file.)

While those descriptions might apply to almost every child, and quite a few adults, the key is that these behaviours must:

  • have had their onset in early childhood (before age seven or 12, depending on the criteria being applied),
  • be excessive for a child’s age and developmental level,
  • have persisted for at least six months,
  • be in evidence not just at home but in other settings such as school,
  • have no obvious alternative diagnosis,
  • and most importantly, must be causing significant functional impairment.
  • There are also a number of ADHD subtypes, including inattentive ADHD, predominantly hyperactive-impulsive ADHD or the combined.

“ADHD is really about inattention, impulsiveness and hyperactivity,” Thomas says.

“People often miss the inattention ADHD by itself because the children are behaving well,” she says. But these children may still have ADHD and a missed diagnosis could have long-term consequences for their learning and development.

“It’s the inability to attend, the inability to sit and work through something and then because they get reinforced by not being able to do something, the they’re less likely to keep trying,” Thomas says,

The more common image we associate with ADHD is one of extremely disruptive children, but Thomas says these so-called externalising behaviours, such as aggression and defiance, aren’t always a sign of ADHD.

“Parents go and see these clinicians predominantly because of the externalising behaviours and teachers recognise kids because of the externalising behaviours because they mess up the classroom, whereas they miss the inattention stuff a lot of the time,” she says. Read more.

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