There is something particularly polarising about adolescent attention deficit hyperactivity disorder (ADHD): be it the diagnostic criteria, the pharmaceutical interventions, the symptomology, even the disorder itself.
In 1798, Scottish physician Sir Alexander Crichton published a series of books based on clinical cases of mental illness from observations during his clinical practice in hospitals throughout Western Europe. The result is the ‘succinctly’ titled series: An inquiry into the nature and origin of mental derangement: comprehending a concise system of the physiology and pathology of the human mind and a history of the passions and their effects.
As part of this series, Crichton was the first to define an alteration of attention as, “the incapacity of attending with a necessary degree of constancy to any one object”, which is not too far removed from criteria found in the latest iteration of the Diagnostic and Statistical Manual of Mental Disorders (DSM), now in its firth edition.
From Crichton’s initial observation of an alteration of attention to the latest definition, ADHD, the clinical understanding of inattentiveness evolved along this timeline: a defect of moral control (1902), postencephalitic behaviour disorder (1908), hyperkinetic disease of infancy (1932), minimal brain damage (1920s), minimal brain dysfunction (1960s), hyperkinetic reaction of childhood (1960s), attention deficit disorder – with and without hyperactivity – (1980s), attention deficit hyperactivity disorder (1978, 1994, 2000, 2013).
There are two publications on which a mental health diagnosis is based – the International Classification of Diseases (ICD) published by the World Health Organisation or the DSM published by the American Psychiatric Association. The rationale for using these publications is diagnostic reliability and validity.
The DSM is favoured over the ICD in Australia for a mental health diagnosis. If an individual is to be diagnosed with ADHD, their diagnosis will be based on the criteria in the latest version of DSM.
The first edition of the DSM was published in 1952 with a remit to standardise the definitions of mental disorders, however, it was far from an ideal source, for instance, homosexuality was listed as symptomology of a sociopathic personality disturbance.
As for ADHD and the DSM, it was initially termed hyperkinetic reaction of childhood in the second edition (1968), renamed to ADD, with or without hyperactivity, in the third edition (1980) and ADHD by the fourth edition (1994), which was carried over to the current fifth edition (2013).
As the understanding of ADHD has developed since Crichton, some of the misunderstandings are still evident. However, instead of the clinical definition of the disorder being the source of consternation, the focus of debate is on the number of adolescents being diagnosed, the accuracy of these diagnoses and the long-term effects from the pharmaceutical interventions.
Beyond adolescence
As ADHD has become more widely understood, so, too, has the prevalence and longevity of the disorder according to Professor David Coghill, who has been involved in clinical care in his role as child and adolescent psychiatrist and researcher of ADHD for more than 20 years.
Prof Coghill is the Chair of Developmental Mental Health at The Royal Children’s Hospital, Melbourne, Vice President of the Australian ADHD Professionals Association and is one of the editors of the Oxford Textbook of Attention Deficit Hyperactivity Disorder.
When Prof Coghill started to see cases, the general understanding of ADHD was that it was a disorder affecting primary school aged children, however, over time it became clear this was not the case.
“Clinically, my understanding of ADHD in adolescents came from watching these kids grow up and realising that it did not just suddenly disappear when they went to high school. In many cases this was when the condition became more complicated.
“We now realise that an awful lot of adolescents with ADHD will become adults who also have it. Not everyone, but many will continue to have problems. Even if they do not have the full set of ADHD symptoms, they will continue to have significant impairments,” Prof Coghill explained.
He said ADHD was both a mental health and neurodevelopmental disorder and attempting to make a distinction was difficult and not particularly helpful.
“ADHD is a constellation of difficulties in its classic form: poor attention, concentration, impulsivity and overactivity. Of course, all kids and all of us have problems in some of those domains over time, but those with ADHD have significant difficulties in inattention, concentration, impulsivity and hyperactivity that has caused problems across multiple parts of their lives.”
Prof Coghill explained that although ADHD symptomology is inherently heterogeneous and complex between individuals, in general, enough common themes, symptoms and problems will become apparent to make a reliable diagnosis.
“These problems manifest themselves in very different ways, such as an interaction between the person and their environment, their family, their underlying strengths and difficulties,” he said.
“ADHD is a complex condition and often becomes more complex the older someone becomes because they lose a lot of the supports, structures and scaffolding they had when they were younger.”
By the end of adolescence, a quarter of diagnosed children will still meet the full criteria for ADHD, while about two thirds will still have considerable ADHD-associated impairments.
“Adolescents with ADHD will develop, they will have better concentration when they are 14 compared to when they were five, but they are still falling behind the expected norms of development,” he said.
While ADHD presents as a diagnosis, the associated problems are what tends to interfere with individuals’ lives and development, Prof Coghill explained.
“The real issues come in the associated problems: Adolescents with ADHD have a higher risk of educational failure, trouble with the law and breaking rules, being victims of abuse, increased rates of self-harm and suicide, substance misuse and depression and anxiety.”
Diagnostic reliability
Reliability and validity should be the foundations of an evidence-based diagnosis, yet unlike a physical morbidity that can be scanned or tested, an ADHD diagnoses is based on the clinician’s perception from an examination, the patient’s self-reported behaviours and the DSM criteria. None of which is as conclusive as an MRI or blood test.
Nevertheless, ADHD is one of the most reliable diagnoses in the DSM, along with autism and severe cognitive difficulties, says Prof Coghill.
“When you look at DSM disorders, the reliability of making the diagnosis depends on a good quality assessment and being trained to do such an assessment, but the reliability of an ADHD diagnosis when done properly is really good.”
Increasing rates of diagnosis
A common criticism of the increasing rates of ADHD diagnosis is a result of pathologising adolescent behaviour leading to over-diagnosing. Prof Coghill believes the reality is the opposite.
“Although there has been an increase in the rate of diagnosis in Australia, it is much lower than the epidemiological rates suggest. The estimated prevalence of ADHD in the community is about 7%, the global figure is about 5%, he said.
Whilst the exact figures of ADHD diagnosis in Australia is difficult to know, Prof Coghill estimates the rate of diagnosis in Australia to be 2%, which would suggest about 40% of children with ADHD are being diagnosed.
As to why so many adolescents go undiagnosed, he sees this partly as an issue of workforce capacity with most child and adolescent diagnoses being made by paediatricians, whilst the public mental health system is under significant pressure due to funding and resource limitations.
“Child and adolescent mental health services have been seriously underfunded, with most of the funding coming from the state. Consequently, they have stepped back from working with ADHD,” he said.
“This has meant that most of the work in this space is conducted within the private system where there are many more paediatricians than there are child and adolescent psychiatrists. Access to these private services is more restricted for those with limited means.
“It also means that those training and working within the public systems miss out on important learning about recognising and managing ADHD when it presents in the public specialist mental health settings because it is often missed and untreated.
“If we could bring together these fragmented systems, we would take a big step towards helping those with ADHD.”
Focused treatment
The most contentious treatment for ADHD also happens to be the most effective: pharmacotherapy. However, Prof Coghill emphasised it should not be the first intervention.
“Certainly, the evidence base is much stronger for medication treatment, particularly in adolescents and adults, than it is for non-medical treatments, but we must be careful. The first treatment for ADHD should be psycho-education, support and adjusting people’s lives to allow them to function and manage better and to deal with their ADHD.”
This type of approach focuses on the way parents organise their children’s days, activities outside of the home and how to manage them in classrooms.
“These kinds of accommodations and support, along with clear psycho-education of the child, their parents, teachers and families to understand what ADHD is and to understand, for example, that many of the difficulties that a young person has is because they can’t do something as well as others of their age, rather than they will not do something at all,” he said.
“For example, when it comes to doing homework, it can be a real struggle for that young person to engage in that activity, to engage in less structured learning. So that is really the key beginning of treatment. However, support on its own is not usually enough to help people manage their ADHD.”
When this support is not enough, pharmacotherapy is introduced, in conjunction with the accommodations and psycho-education.
“There is almost unanimous agreement amongst countries, along with national evidence-based guidelines, that for adolescents with ADHD, if the support is not helpful, then you should be thinking about medication as part of the treatment,”
Prof Coghill said.
“For younger children, parent training programs are good at reducing oppositional behaviour, improving cognitive parenting and reducing negative parenting. The interventions that we have got can provide important support to improve important parts of their lives but are not particularly effective at reducing the ADHD symptoms and that is why the medications are used.”
As to which medications are most effective, two classes of stimulants are most effective, methylphenidate and amphetamines, such as dexamphetamine. However, which drug is the most suitable will be individual, Prof Coghill explained.
“We know that about 70% of people have a good response to methylphenidate and about 70% of people have a good response to amphetamines. Between 90 and 95% will have a good response to one or the other. It is not either one or the other, there are people who respond better to one or the other, but we cannot tell without trying, unfortunately.”
Kids will be kids
This well-worn adage serves to normalise and generalise the mercurial, frenetic, and challenging behaviour of children during their development. Clinically, adages tend not to inform interventions, but in the case of ADHD diagnoses maybe they should, says Dr Martin Whitely.
Dr Whitely is a researcher at Curtin University and was a teacher and a former member of the Western Australian Parliament. Throughout his political and research careers, Dr Whitely has been a prominent critic of ADHD prescribing for children and adolescents.
Diagnosis by age
Research led by Dr Whitely, published in the MJA in 2017, that found that the youngest children in Western Australian primary school classrooms (born in June) were twice as likely to be diagnosed with ADHD than their oldest classmates (born the previous July). 2019 research also led by Dr Whitely found similar relative age effects in 13 countries, including corresponding low (e.g. Finland, Sweden) and high (e.g. USA, Canada) rates of prescribing ADHD medications.
Boys were also three to four times more likely to be medicated for ADHD than girls.
“So, Oliver, one of the youngest boys in his class is many times more likely than Amy, one of Oliver’s oldest classmates, to be prescribed amphetamine-type stimulants,” Dr Whitely told Medical Forum. “We treat Oliver’s perfectly normal age and gender-related immaturity as if it is a disease,” he added.
Broken system
Is this a systemic failure of both the health care and education systems? According to Dr Whitely, the answer is yes.
“We should expect younger children, particularly boys like Oliver, to be less mature – and frankly maybe a bit more annoying – than their older classmates. Our schools and health system should cater for this difference and not medicalise it.”
Dr Whitely believes the fact that the ADHD late birthdate happens across the globe in both high and low prescribing countries makes a mockery of this claim that we just need to tackle over prescribing: “It indicates the diagnosis is fundamentally flawed.”
“We have embraced this reductionist approach that says ADHD type behaviours are likely caused by a series of biochemical reactions requiring medication.”
Dr Whitely concedes that could be true in some cases but argues this theory “is nothing more than an unproven hypothesis”.
He believes there is too much emphasis on the use of medications for short-term behaviour management rather than on long-term outcomes: “What is missing in the ADHD debate is a systematic, independent, robust evaluation of the long-term outcomes associated with medications.”
Dr Whitely says he would love to co-operate with researchers “on the other side of the ADHD debate” to develop long-term evidence of medication safety and efficacy “that could be trusted”.
His interest in ADHD came from his years in the classroom, teaching at a private school which, according to him, there were high rates of children on ADHD medications.
“I had 14-year-old medicated boys sitting unnaturally quietly and obediently in class. The medication made them subdued and easy to control but it did not seem to be helping them academically,” he said.
Dr Whitely said when he first became concerned about ADHD he had no medical training and didn’t feel he could challenge the experts. “But I soon came to realise there is no hard science in the DSM-based diagnostic process.”
During his time in politics and after as an academic, Dr Whitely has been a strong opponent of ADHD medication of children and is focused on the long-term harm associated with stimulants.
Problematic prescribing
Dr Whitely, has also recently co-authored research examining West Australia’s history of amphetamine prescribing for ADHD and its diversion for illicit use. He said there was direct evidence of the illicit use of prescribed simulants, primarily dexamphetamine, by WA teenagers which he attributes to liberal prescribing of ADHD medications.
His 2020 study found that in WA in 2017, 3% of students aged 12 to 17 years reported they had used dexamphetamine for non-medical purposes. However, only 1.2% of this population was prescribed the drugs.
“There is no doubt that we have a significant problem with prescription amphetamines being used illicitly by WA teenagers,” he said.
Dr Whitely said that this was particularly disappointing because regulatory moves he sponsored through state parliament when he was a member in 2003 have been weakened.
“Back then, data showed a paediatrician prescribed ADHD medication to 2077 children over a 17-month period. This set off alarm bells so we acted and by 2010 the WA prescribing rates to children fell by 50%.”
He said that in 2015, the last year for which individual clinician prescribing data was published, a single WA psychiatrist prescribed stimulants to 2074 patients. “It’s history repeating.”
His 2020 study found that for at least two decades WA has had the highest rates of prescribing ADHD medications (primarily dexamphetamine) to adults in the country. The latest data indicates that in 2017 WA adults were 2.6 times more likely to take ADHD medications than elsewhere in Australia.
“WA has also consistently reported high rates of illicit amphetamine use. Is it too much of a stretch to suggest the two facts are related?” Dr Whitely asked.