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19 Aug 2014

For the past 20 years Dr David Coghill has been working at the boundaries of understanding child behaviour, helping sort out the distinction between the hijinks and scattiness that are a normal part of growing up with disorders which can lead to lifelong impairment.

It has meant the Scottish-based expert is no stranger to the controversy that surrounds the diagnosis and treatment of attention deficit hyperactivity disorder (ADHD).

As rates of ADHD diagnosis have grown world-wide, so have claims that lazy parents and clueless doctors are turning to drugs to dampen the natural exuberance of children, in the process creating a generation of doped-up zombies.

Dr Coghill, who leads the Developmental Research Group at the University of Dundee’s Division of Neuroscience, has heard it all, and is bluntly dismissive of such fear-mongering.

It is true, he told Australian Medicine, that the diagnosis of ADHD has jumped in recent years, but from a very low base (in Scotland, from just 0.3 per cent of the child population to around 1.2 per cent), and it was still a reasonably rare condition that was hardly suggestive of an epidemic of over-diagnosis.

Instead, Dr Coghill said, the problem was that many more children had the disorder than were being diagnosed, denying them essential treatment.

He said that in Scotland around 5 per cent of children had ADHD, so the diagnosis rate of 1.2 per cent meant the disorder was being significantly under-recognised and treated.

Most of the concerns about rampant over-diagnosis of ADHD have their origins in the United States. While the American Psychiatric Association estimates 5 per cent of children have the disorder, figures compiled by the Centers for Disease Control and Prevention show that around 11 per cent of American children aged between four and 17 years (6.4 million) were diagnosed with the condition as of 2011, with the rate of diagnosis growing by an average of 5 per cent a year.

In Australia, as in Europe and the UK, rates of diagnosis are lower but, unsurprisingly, are influenced by the diagnostic criteria that are applied.

In the US and Australia, the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM) is widely used, while in Europe practitioners have largely the World Health Organisation’s the International Statistical Classification of Diseases (ICD) as a guide to diagnosis.

DSM embodies a more encompassing approach to the diagnosis of ADHD than the ICD. Mutual exclusivity between ADHD and autism was dropped in DSM-5 released last year, and the age of onset of the disorder was raised from before seven years to before 12 years.

By contrast, ICD 10 takes, Dr Coghill said, a more rigid a restrictive view. It identifies hyperkinetic disorder (which he said was akin to what he would describe as severe, persistent and impairing ADHD), while those with lesser symptoms and impairment described as having ADHD. In population terms, 5 per cent of children have ADHD, of whom a subset of 1.8 per cent have hyperkinetic disorder.

Dr Coghill has played a leading role in trying to improvement and refine the diagnosis of ADHD, and was central to the development of European guidelines for the assessment and management of ADHD, and has helped devise a program to assist clinicians to use this guidelines in practise.

Ask most people to describe ADHD and they would mention inattention, poor impulse control and hyperactivity.

But Dr Coghill said that, “on its own, that is not enough”.

“If you looked across the general population you would say everyone has got some of that, and that is correct,” he said, warning that if you relied on these symptoms alone to diagnose the disorder, around a quarter of all children would be classified as having ADHD.

He said that an accurate diagnosis rested not only on a checklist of more than 20 symptoms, but also the level of impairment resulting from this behaviour.

“These symptoms need to be interfering with daily life in a significant way, not only causing problems at home, but also in one other area of life, usually school.”

Dr Coghill said the symptoms of ADHD needed to be present, persistent, to have started early in life and to have caused significant impairment.

It means that accurate diagnosis is not simply a matter of ticking off a list of observed behaviours, but of gathering and assessing information about the patient’s life.

“We are very clear in these guidelines that you need to collect not only information about symptoms, but also a child’s development; how they are managing broader areas of life,” he said.

It means that it is “probably not possible” to make a diagnosis of ADHD in one visit to the doctor, and each consultation was likely to be time consuming.

Dr Coghill acknowledged this as a constraint in the Australian system of primary care, where low fees put the pressure on doctors to churn through patients as quickly as possible.

Just as important as the diagnosis of ADHD is its treatment.

In the US, medication is considered a first-line treatment for the disorder. In almost as third of states, more than three-quarters of children diagnosed with ADHD are being given drugs, according to CDC figures.

Dr Coghill said medication is a front-line treatment for those with severe ADHD.

But he added that evidence, particularly the pivotal Multimodal Treatment of Attention Deficit Hyperactivity Disorder (MTA) study, first published in 1999 and updated in 2009, showed that intensive non-pharmaceutical therapies could be effective as the first line of treatment for those with milder forms of ADHD.

Dr Coghill talked about ADHD diagnosis and treatment with clinicians and researchers in Brisbane, Sydney, Melbourne and Adelaide as part of a four-day visit sponsored by Janssen Pharmaceuticals.

Adrian Rollins

Published: 19 Aug 2014