The Science of ADHD E-Book

Chris Chandler

• Herausgeber: John Wiley & Sons
• Kategorie: Geisteswissenschaft
• Sprache: Englisch

Seitenzahl: 610

Veröffentlichungsjahr: 2011

Beschreibung

The Science of ADHD addresses the scientific status of Attention-Deficit Hyperactivity Disorder in an informed and accessible way, without recourse to emotional or biased viewpoints. The author utilises the very latest studies to present a reasoned account of ADHD and its treatment.

• Provides an up-to-date account of the neuroscience of ADHD, and the limitations of such research
• Addresses the scientific status of ADHD from an objective and evidence-based standpoint without recourse to emotional and uninformed argument
• Describes and discusses the ever increasing scientific evidence
• As a parent of a child with ADHD, the author has first-hand experience of the subject matter, and a unique understanding of the information parents require on the subject

Leseprobe

Table of Contents

Cover

Table of Contents

Dedication

Title page

Copyright page

Boxes, Tables, and Figures

Preface

Acknowledgments

1 What is ADHD?

What Does ADHD Look Like and Who Has It?

ADHD – Two Faces of the Same Coin

The Negative Impact of ADHD

What is ADHD Like?

ADHD: Science and Society

Summary

2 Diagnosis, Epidemiology, and Comorbidity

A Short History of ADHD

Current Diagnosis

DSM-IV vs ICD-10

Is ADHD Real?

Adult ADHD

Is Adult ADHD Real?

Diagnosis and Future Criteria

Assessment

Rating Scales

Epidemiology

Comorbidity – Not Just ADHD

Summary

3 Causality and the Environmental Hypotheses of ADHD

Causality

Animal Models of ADHD

The Environment

Summary

4 Psychological Theories of ADHD

Impulsivity and Behavioral/Response Inhibition

Alerting, Orienting, and Executive Functioning – Separate Circuits in ADHD

Working Memory

The Supervisory Attentional System

Brown’s Executive Functioning Model

The Cognitive-Energetic Model

Summary

5 The Genetics of ADHD

The Evidence for (and against) ADHD as a Genetically Inherited Disorder

Evolution and the Continuation of ADHD

Molecular Genetics

Summary

6 The Neuroscience of ADHD

The Brain: A Brief Guide to Development and Neuroanatomy

Regions of the Brain

A Brief Account of Imaging the Brain

The Brain in ADHD

Structural Changes

Gray and White Matter

The Frontal Lobes

The Basal Ganglia

The Cerebellum

Functional Significance

Functional Imaging of ADHD

Psychophysiological Studies

The Fronto-Striatal Circuits

Summary

7 Psychostimulant Treatment of ADHD

A Brief Review of the Neuropharmacology

Pharmacotherapy in ADHD

The Pharmacology and Efficacy of Psychostimulants Used in Treating ADHD

The Pharmacology of Methylphenidate

The Pharmacology of Amphetamine

Clinical Effects of Methylphenidate and Amphetamine

The MTA Study

Side-Effects of Amphetamine and Methylphenidate

Pemoline

Nicotine

Tolerance and Withdrawal

Psychopharmacology: From Treatment to Theory

Hypo/Hyperfunctioning DA in ADHD

Grace’s Tonic and the Phasic Account of ADHD

A Dynamic Developmental Theory of ADHD

The Rate-Dependent Hypothesis and the Effects of Psychostimulants

Noradrenaline

Summary

8 Non-Stimulant Medications and Non-Pharmacological Treatments

Non-Stimulant Medications

How Do These Drugs Fit into Theoretical Accounts of ADHD?

Non-Pharmacological Treatments

Alternative Treatments

Summary

9 Addiction, Reward, and ADHD

Addiction

Addiction in ADHD

Are ADHD Subtypes Linked to Any Particular Drugs?

Amphetamines, Methylphenidate, and Addiction

Methylphenidate Treatment and Addiction

Drugs, Cannabis, and Psychiatry

Methylphenidate: Slow Release and the Treatment of Cocaine and Amphetamine Addiction

Methylphenidate and Long-Term Neural Changes

Reward Deficiency in ADHD

Impulsivity in SUD and ADHD (Revisited)

Summary

10 The Past, Present, and Future Science of ADHD

Towards a Better Understanding and Treatment of ADHD

What Do the NICE Guidelines on ADHD Really State?

Glossary

References

Index

To Max and Guy

This edition first published 2010

© 2010 Chris Chandler

Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing program has been merged with Wiley’s global Scientific, Technical, and Medical business to form Wiley-Blackwell.

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Library of Congress Cataloging-in-Publication Data

Chandler, Chris, 1966–

 The science of ADHD : a guide for parents and professionals / Chris Chandler.

p. ; cm.

 Includes bibliographical references and index.

 ISBN 978-1-4051-6234-0 (hardback : alk. paper) – ISBN 978-1-4051-6235-7 (pbk. : alk. paper) – ISBN 978-1-4443-4150-8 (ebk) – ISBN 978-1-4443-4081-5 (ebk)

 1. Attention-deficit hyperactivity disorder. I. Title.

 [DNLM: 1. Attention Deficit Disorder with Hyperactivity. WS 350.8.A8 C455s 2011]

 RJ506.H9C47 2011

 618.92'8589–dc22

2010011917

A catalog record for this book is available from the British Library.

Boxes, Tables, and Figures

Boxes

2.1 The DSM-IV diagnostic criteria for ADHD

2.2 ICD-10 criteria for hyperkinetic disorders

Tables

1.1 The three key symptoms of ADHD

2.1 Conditions that may present as similar to ADHD but are not ADHD

2.2 The Utah criteria for adult ADHD

7.1 Release rate of methylphenidate in different extended- release preparations (the Rubina Chart)

Figures

2.1 The circular relationship between science and diagnosis

2.2 The input needed to make a diagnosis

2.3 The role of biological, social, and psychological factors in the manifestation of the triad of symptoms seen in ADHD

4.1 The endophenotype

4.2 Behavioral inhibition

4.3 The Stop-Signal Reaction Time task (SSRT) and Go/No-go task

4.4 Working memory

6.1 The cortical regions of the brain

6.2 The limbic system

6.3 The regions of the basal ganglia

6.4 The regions of the frontal cortex communicate with striatal regions, which go on to communicate with other regions of the basal ganglia and the thalamus

7.1 The neuron

7.2 The action potential

7.3 Dopamine and noradrenaline synthesis and metabolism

7.4 A normal unaffected dopaminergic synapse

7.5 The effects of amphetamine and methylphenidate on the neuron

Preface

Not another book on ADHD! This is perhaps the groan that will greet this publication. A quick look at Amazon.com indicates that this subject has been written about extensively. So – why another book?

The reasons are as follows:

In 1998 our first child was born. He was (and still is) a joy. However, after a couple of years we started to realize he was different. He had the energy and stamina of a superhero; he could walk for several miles by the time he was 3 (although running was his chosen form of movement). His activity was not a cause for concern, we would just accommodate his needs, and as new parents we considered this to be fine; we did not have a comparison. In fact we thought other children were inert and slightly boring! Excitement and activity were to be with us for sometime to come, shortly to be joined by stress and anxiety. But it was not just his zest for life and his activity that were noticeable; he was also starting to show signs of being impulsive and disorganized. He would react to others around him very quickly and often respond physically and sometimes aggressively. He would try to use physical force to get to his goal rather than thinking and problem solving. Although his behavior was not initially a problem in its own right (after all, boys will be boys), it was starting to become an issue not only with us as parents, but also with others who would occasionally care for him and eventually teach him. We became the parents the teachers always wanted to speak with after school.

In common with many others, but suffering in isolation – the loneliness that comes with differences can be acute – we realized that our son’s individuality, or, as they were to become, his difficulties, were preventing full participation and integration within the wider social world, and, more worryingly, were severely restricting his education. To cut a long, and possibly familiar, story short, we went through the multiple processes of evaluation and diagnosis. Eventually, his consultant psychiatrist awarded him the diagnosis of ADHD that we had suspected now for some time. It may appear curious that I use the word awarded as it may imply a prize or goal. But it was an award, and a reward for all the hard work that went into his evaluation. He is now an expert at the psychometric tests. Along with diagnosis came treatment. We had tried a number of behavioral techniques with him, but after the diagnosis came methylphenidate (Ritalin). Methylphenidate is a notorious drug with a controversial history. Stories of addiction and worse were never far away. If the drug works, that’s great, but how does it work? and what does it do? are important questions to resolve.

I am a psychobiologist by trade – that means I study the biological underpinnings of behavior. I am also a concerned parent, and as any anxious parent who has to make a decision about their child’s health, I wanted to find out more about ADHD and its treatment. I thought I would get a good book that would explain it all to me – wrong! I was greeted with a lot of books, none of which had the answers I required. Many were books about the demise of a past society and the creation of a modern fast-paced society full of bad parents. On the back cover of Angela Southall’s book in bold it states “This is not just another book on ADHD. This book tells the side of the story most of us are otherwise unlikely to hear.” However, Southall puts forward a similar set of arguments about ADHD that a great majority of other anti-psychiatry books do, she just does it in one entertaining and intuitively appealing volume [1]. These books did tell me about the horrors of methylphenidate and that parents and society are ultimately to blame. Many of the books are selective in their use of evidence – a criticism that the authors will no doubt direct at me.

As a result of my dissatisfaction with the available books, I went back to the original sources of information. This information is in the scientific and medical journals where new investigations on ADHD are published. This is not an exercise for the faint-hearted, As Ida Sue Baron points out, “the extensive literature regarding Attention-Deficit/Hyperactivity Disorder (ADHD) is often overwhelming, even to those most knowledgeable about this behavioural disorder” [2] (p. 1). Apart from the sheer volume of information that is available, anyone who has tried to read such papers will immediately know that they are often difficult to comprehend and focus on the small details of ADHD. This dissatisfaction with the accessible knowledge regarding ADHD prompted me to write this book. My intention is to inform parents, students, academics, clinicians, educators, and most importantly those diagnosed with ADHD with a clear account of this complex disorder and its treatment and dispel some of the erroneous assumptions that can be prevalent (e.g. [3–5]).

Like all people, I come with my own ideas and views on ADHD. As a psychobiologist, I approach the study and discussion of ADHD from a neuroscientific position: that is, a brain perspective or the medical model. Having admitted to a bias towards the medical model, I also have a view on the rapidly changing world around me, and I share the sympathies of those individuals who suggest these changes in our lifestyle have an impact. I do not subscribe to the notion that our environments and our biology are separate: nature and nurture cannot be untangled so simplistically (if they can at all!).

The simplistic notion that the world is too busy and there is an over-stimulation of the senses to which we react is an attractive hypothesis. We can all feel the bombardment of our senses and the stress that it can produce in western society (and beyond). But do these changes cause ADHD? Even if they do, why is it that most children (or adults) can manage within this changing society? Ultimately, why do some individuals get ADHD and others do not? Is there a common cause of ADHD? Is there a common change in the brain? Is there hope? And is there a cure?

The questions are endless, though many can attempt to be answered. But for every question answered, many questions still remain and even more are created in the fine detail of ADHD research. The pursuit of knowledge and understanding is therefore endless, and this is exemplified in the case of ADHD. Finally, the complexities of the brain are still as yet to be unraveled. It is surprising given the brain’s complexity that some people, many of whom are non-experts, will pass comment/judgment on the brain’s output (behavior). As Lyall Watson said, “If the brain were so simple we could understand it, we would be so simple we couldn’t.”

I hope that this book explains some of the science behind ADHD, as well as its limitations, and empowers people with the knowledge that will move them away from the bar-room debates and playground comments to a more educated and informed level.

Acknowledgments

At the top of the list of those I need to thank is my wife, Diane. She has supported me in this venture and has given me much cause for thought and reappraisal of my views on ADHD, this book, and life generally. Her love and kindness are always appreciated.

Next up are my lovely boys, Max and Guy, who have been such a joy and inspiration. Of all the people in my life it is these two who have had the biggest influence. And without Max I would not have attempted this book. Thanks, Max.

I would also like to thank Jo Lusher, Carl Bate, and Sean O’Brien for maintaining my sanity and keeping me firmly based in reality. Thanks to Lou for keeping the beer flowing. Cheers!

Staff at Wiley-Blackwell have supported me and given me help, advice, and encouragement – even when the deadline was long overdue. Special thanks to Karen Shield, Andrew McAleer, and Annie Rose.

I would like to thank numerous colleagues for the conversations we have had that have made a difference to my thinking during the writing of this book (although they may not know it!). Thanks are also due to those I have spoken to at conferences and meetings who have helped with my thoughts – too many to mention. Finally, I am grateful to all the authors who sent me copies of their work (again too many to mention). Without their help this would have been a far more difficult enterprise. It is their work that is inspiring and thought provoking.

1

What is ADHD?

Attention Deficit Hyperactivity Disorder (ADHD) is not one symptom or even two symptoms, as the name might suggest. ADHD is not just deficient attention or excessive activity; it is a cluster of behaviors that are, more often than not, seen together. Thus ADHD is a syndrome comprising of several, presumably connected, symptoms.

The main behaviors observed in an individual with ADHD are impulsivity, inattention, and hyperactivity. These three are the key characteristics of ADHD, but as we shall see when we look at diagnosis (see chapter 2), this triad of behaviors is not always its absolute defining characteristic. For example, ADHD can occur without the hyperactivity being present – so children do not have to be running around and bouncing off of the walls all the time in order to have the condition. Or ADHD can be primarily about impulsivity, which the title of the disorder does not allude to. Impulsivity may be one of the greatest handicaps in the range of behaviors seen in ADHD (see chapter 4). Furthermore, until recently ADHD has been seen exclusively as a childhood disorder – a disorder that the child may eventually grow out of over time. Over the last 15 to 20 years, however, research and clinical experience have been able to challenge this assumption by defining and identifying ADHD in adults.

One could be forgiven for thinking that ADHD is a recent phenomenon emerging during the past 20 to 30 years. Certainly there has been a dramatic increase in the diagnosis and treatment of ADHD, but is it a new disorder? The answer is most certainly no. The impact of ADHD may be greater than at other points in time, but it is not new. Indeed, early reports in the medical literature providing accounts of individuals demonstrating the behaviors associated with what we now call ADHD can be found at the beginning of the twentieth century.

Throughout the last century, and especially in the last 30 years, there have been a number of differing perspectives on the cause of ADHD. These perspectives are wide-ranging, including societal causes (typified by such books as The Ritalin Nation by Richard DeGrandpre [6]), neurobiological causes (e.g. [7]), through to evolutionary/genetic theories that claim ADHD is a result of behaviors that were useful in our ancestry, but that may now have little relevance in a modern-day westernized world [8].

Most accounts of ADHD in the scientific literature begin with describing the disorder as a complex neurobehavioral problem with a genetic component. The weight of the evidence supports this supposition. However, science is not without bias itself. Some have argued that there is a bias towards funding research that is medically oriented. We must remember that science, like everything else, does not take place in a cultural vacuum. Why, then, does the science not reach the media, the education systems, and even the medical professions? In short, science can be more difficult to comprehend than other explanations, which lend themselves to our own inherent biases and opinions.

So what is ADHD? It is a neurobehavioral disorder of great complexity; it is a disorder with a genetic pedigree; it is a disorder in which environmental conditions can exacerbate or ameliorate the symptoms; it is a disorder which has considerable impact on the life’s of those diagnosed with it, but also those who live/work/study/interact with someone diagnosed with the disorder; it is a disorder which can in many cases be treated; it is a disorder that is most likely going to persist into adulthood; it is a disorder which is often seen with other disorders; and it is a disorder that requires further research for a greater understanding.

What Does ADHD Look Like and Who Has It?

One might expect to gain the answer from a review of diagnosis. However, this question is different from the question of clinical diagnosis (see chapter 2). The diagnostic criteria of ADHD do not do justice to a description of ADHD and what it is like to live with the disorder. Diagnostic criteria can be dry lists that lack detailed descriptions. Furthermore, there is a tendency for the symptom lists to be presented to the lay reader without a context or explanation of the process involved in the assessment. ADHD can have positive and negative qualities – although its negative components are the ones that impact most on normal functioning and are the most prominent; after all, psychiatry is concerned with deviation from normality and therefore they receive the greatest amount of press.