The second edition of this book takes account of growing knowledge in neuroscience, the recent changes in classification of psychiatric disorders, and an increasing range of treatment opportunities. It comes at a time when the diagnosis in most countries is made more frequently than ever before—with a corresponding public anxiety that the diagnosis is made too often. Developmental science has found that ADHD often persists into adult life and this has led to an increasing clinical recognition of the problem in adults.
The concepts of ADHD originally developed from the long-standing recognition that some children and young people are hard to control and are unable to control themselves. From the early nineteenth century, Benjamin Rush in the USA, Alexander Crichton in Scotland, Désiré-Magloire Bourneville in France, and George Frederick Still in England were among those who wrote in clinical terms about failures of self-control as problems for development (Taylor 2011). The language used became more refined, and new concepts appeared—for example, ‘hyperkinetic syndrome’ from Kramer and Pollnow, and ‘minimal brain dysfunction’ from authors such as Tredgold. These new concepts tied together the ideas of motor dyscontrol and behavioural dysregulation.
The discovery of the therapeutic actions of the amphetamines made it clearer that they affected a triad of restless overactivity, impulsiveness, and inattentiveness (Taylor 2011). The need to measure the effects of treatment led to systematized rating scales, and statistical analysis of the questionnaires confirmed that the triad of behaviours did indeed occur together. Longitudinal studies showed that they tended to persist and to be impairing, and clinical research showed that they predicted consistently to cognitive changes and were susceptible to treatment (Taylor and Sonuga-Barke 2008). In all these respects, the behaviours make up a valid psychiatric condition. It exists as ‘attention deficit/hyperactivity disorder’ in the Diagnostic and Statistical Manual of the American Psychiatric Association (DSM5) and ‘hyperkinetic disorder’ in the WHO’s International Classification of Disease (ICD 10). A major systematic review of the scientific evidence concluded that it is indeed a valid way of describing a common and impairing mental health condition in children, adolescents, and adults (NICE 2009).
We now have the benefits of standardized rating scales to help in assessment and in monitoring of progress (see Chapter 4), an extensive literature of experiments that demonstrate and analyse cognitive changes (see Chapter 3), a range of effective medicines, both stimulants and non-stimulants (see Chapter 5), knowledge of psychological methods to reduce the behavioural problems that often accompany ADHD (see Chapter 6), guidelines based on systematic reviews about how to use the various treatments in practice (see Chapter 7), and understanding how the problems affect adults (see Chapter 8). Readers of this book will find that they are equipped to make a real and helpful difference to the lives of affected children.
Nevertheless, and in spite of those advances, ADHD remains a controversial topic. Many educators, journalists, and politicians in Europe have expressed a suspicion that the definition is too vague and subjective, and allows a medical concept to be applied to children who are, in fact, developing normally; that medication is being used too much; and that the fifth revision of the Diagnostic and Statistical Manual of the American Psychiatric Association is exacerbating all these trends. Diagnosis and medication are increasing in frequency, especially in the USA (Visser et al. 2014). Serious journalism1 has raised important questions, including the following:
• Why do rates of diagnosis and treatment vary so much from place to place and at different times?
• How frequently should ADHD be diagnosed and treated?
• Why are there no objective tests, and does this invalidate the diagnosis?
• Why is there no satisfactory cut-off to demarcate those with and those without ADHD?
These are issues, not only for ADHD and hyperkinetic disorder, but for psychiatric diagnosis generally. We do not yet have a full understanding of the underlying physiological processes (though progress is being made; see Chapter 3). Accordingly, the diagnosis depends entirely on the clinical presentation and we have nothing like a blood test to give a reassuringly ‘objective’ answer. This means that the clinical presentation has to be deeply understood—Chapter 2 gives a clear account.
The questions above also arise from a common background. The behaviours constituting ADHD are continuously distributed in the population. They seem to constitute a dimension (or set of dimensions) rather than a categorically distinct condition. The borderlines between normal development, atypical development, and overt disorder are not absolute but reflect the extent to which the behaviours interfere with normal life. This situation is in no way unique: the same applies to conditions such as autism, oppositional behaviour problems, and anxiety states. Indeed, it is a common situation in physical medicine. A raised blood pressure, for instance, is on a continuum with normal levels. The clinical decision about the level at which it should be regarded as a disorder is taken in the context of the individual’s age, and the level of risk that it imposes for later health. Psychiatric judgement, too, needs to be based on clinical experience and knowledge. Chapter 2 explains the issues involved. The consensus of experts becomes embodied in classification systems, in evidence-based treatment recommendations, and in the kind of authoritative field accounts that readers will find in the succeeding chapters.
Cultural factors also play a part. The rates of diagnosis and medication in the USA are much higher than in Europe, and to a worrying extent (Rapoport 2013). European countries differ but in most, the rates are about one-tenth of those in the USA. By contrast, the epidemiological data suggest that the actual problems occur at much the same rate on both sides of the Atlantic (Polanczyk et al. 2007).
There are some good reasons for the European clinicians’ caution. A specialist assessment is usually provided in Europe, and if this finds an underlying cause (such as a hearing difficulty or chronic sleeplessness or a learning problem) then that can be treated (see Chapter 4). Many European countries value psychological interventions above pharmacological ones, and in publicly funded systems there are often few obstacles (other than shortage of professionals) to accessing psychotherapies (see Chapter 7 for organizing services and Chapter 6 for how psychotherapies work and can be delivered). Unfortunately, there are bad reasons too for a low use of medication in parts of Europe. Recognition of ADHD is patchy and services are sometimes limited by a lack of professional time. Lazy journalism can spread the idea that the USA style of overtreatment occurs in European countries too, and may generalize even to arguing against the existence of ADHD problems. Accurate information presented to the public is therefore needed, and this book seeks to be a resource for those who are seeking to inform health education.
The major diagnostic schemes are being revised. The American DSM is the most influential and its fifth revision has recently been published (APA 2013). The World Health Organization’s ICD10 is in the process of revision. The basic idea, of a triad of inattentiveness, impulsiveness, and restless overactivity, has not been changed; it has worked well in scientific and clinical study. DSM5, however, does relocate it from being considered as a childhood disorder to a neurodevelopmental disorder that can cause problems across the lifespan. This reflects increased knowledge about the existence and impact of ADHD in adult life (see Chapters 2 and 8). The criteria for recognition in adult life have been relaxed a little, and it has been recognized that the childhood antecedents of ADHD can in fact be the symptoms rather than any impairment arising from them. It has also become clearer that ADHD can still be recognized and treated when other conditions are present as well, and autism spectrum disorder is no longer considered to exclude the diagnosis of ADHD, but to be a comorbidity with it.
Priorities in therapy have also needed re-evaluation. The high priority given to behavioural parent training by existing guidelines (e.g. NICE 2009) may need reconsideration in the light of meta-analysis. The value of nutritional approaches—previously discounted—may need to be upgraded in the light of recent reviews. New drugs are appearing in Europe: the pro-drug lisdexamfetamine and guanfacine have received substantial trials, and lisdexamfetamine has achieved a marketing licence for children and for adults who were treated when they were children. Chapter 5 has been correspondingly updated. Considerations of cost-effectiveness have become particularly important for publicly funded services in a period of economic recession and austerity.
Increasing numbers of affected adults are presenting themselves to psychiatry for the first time in adult life. They sometimes meet services that are unprepared, a situation in which no medicines for their needs are yet licensed in Europe, and a sceptical approach by many professionals. They combine with an increasing number of diagnosed young people who are reaching an age at which adult services should be involved. Clinical guidance for this adult age group would therefore be helpful, even in the absence of the strong evidence from longitudinal studies and treatment trials that has been developed for children and adolescents. A new section (Chapter 8) has been written for this edition to propose recommendations for management in adult life.
The last word has not, of course, been written. There are still areas of real uncertainty. One of the largest is how we should think about children who show no hyperactivity at all, but are nevertheless handicapped by serious problems of inattention. In DSM-IV they were considered as a subtype of ADHD, but later research found very little difference between the different ‘subtypes’. This is probably because the definition of ‘inattentive subtype’ allowed for a considerable amount of overactivity and impulsiveness to be present (up to five out of nine possible symptoms). This means that a new generation of study is needed to find a better account of those people who are not overactive at all, yet still cannot concentrate appropriately.
Other uncertainties that research should clarify include the establishment of ‘objective’ biomarkers, measures of severity that describe impairment in the real world, validated cut-offs to demarcate those who have a disorder from those who do not, and a better understanding of emotional (as well as behavioural and cognitive) dysregulation. DSM5 has created a new disorder, ‘disruptive mood dysregulation disorder’, which is defined by emotional dysregulation, severe irritability, and dysphoria. It is nearly always ‘comorbid’ with ADHD but predicts mood disorder later. Research can be expected to cast light on it, and therefore on how to help young people with ADHD who have this extra problem. We can also expect progress in learning to use neuroimaging, cognitive testing—and eventually genetic analysis—to identify different types of ADHD. Longitudinal research will help clinicians understand what environmental influences are involved in development over time, and which are susceptible to modification. We shall probably come to learn how to use neuroscience methods to predict and monitor the effects of treatment. All these advances in knowledge would lead to the improvement of our ability to help people to understand and overcome their disability. Nevertheless, many affected people are already having their lives transformed by the work already done and described in the succeeding chapters.
The authors of this book have been at the forefront of clinical science. They are unified by membership of a European network, EUNETHYDIS, led by Professor Sergeant. The network has enabled them to meet together, to make systematic and critical reviews of the international literature, to develop published guidelines, and to join basic scientists in multicentre genetic and neuropsychological research.
This book provides a concise and authoritative account of modern knowledge about hyperkinetic disorder and ADHD. It is recommended to all those who need to know about them.
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1 E.g. by Alan Schwartz; New York Times, 14 December 2013.