Understanding and explaining Attention Deficit Hyperactivity Disorder

Speaker: Prof. David Daley (Nottingham Trent University)
Chair: Prof. Jan Buitelaar (Radboud University Medical Center / Donders Institute, Nijmegen)

Jan Buitelaar

[00:00:00] Hello everyone. It's my pleasure to welcome you at this first webinar of a series of webinars organized by the World Federation of ADHD. My name is Jan Buitelaar, I'm a child psychiatrist and adult psychiatrist working in Nijmegen in the Netherlands, and I'm affiliated with the Donders Institute.

[00:00:18] And it's my great pleasure to introduce the speaker of today, which is Professor David Daley. He's originally from Ireland. He did his bachelor's and after that he obtained his PhD, his PhD in Nottingham in the United, sorry, in Southampton in the United Kingdom. And since July 2022, he's a professor of psychological intervention and knowledge exchange at Nottingham Trent University in the United Kingdom. He's a well-known expert in the field of ADHD, particularly clinically oriented. His interest is in non-shared environmental influences on child and adolescent psychiatry and child and adolescent development within the context of neurodiversity. He also pioneered some behavioural intervention studies, and today he will introduce to you the topic of ADHD: Understanding and Explaining Attention-Deficit/Hyperactivity Disorder.

[00:01:20] I will ask you all to switch off your video and to mute your microphone. If you have questions, write them in the chat. And then in the last 10 to 12 minutes, we'll take up these questions. I will pass them on to Professor Daley, and we will close the whole session on the hour. So Dave, the floor is yours.

David Daley

[00:01:46] Yeah, thank you very much, and hello everyone. Thank you for joining us for this first of a series of webinars. As co-chair of the Education Committee for the World Federation of ADHD, along with my wonderful co-chair, Dr Barbara Franke, we have developed a series of seminars that we think will be useful, especially for clinicians who are working with children with ADHD who may not feel that they have sufficient knowledge or understanding of the disorder.

[00:02:17] Whenever you go to training events or conferences, it's usually about the new things. And this series of webinars that we have developed is very much about a return to basics. What do we need? What do we need clinicians to understand and know about ADHD in order for them to be better able to support children that they're working with?

[00:02:40] Today is the first seminar and I'm really just the warm-up act. I'm going to go over lots of things that we need to know about ADHD. Then on the 21st of October, we have Professor Steve Faraone, who's going to talk about misconceptions and stigma. On the 18th of November, we have Professor Barbara van den Hoofdakker, who's going to talk about the impact of ADHD on parents, grandparents and carers. And on the 16th of December we have Professor Luis Rohde, who's going to talk about diagnosis, how to diagnose ADHD in people and how to do that in the presence of other comorbidities.

[00:03:22] We have got lots more seminars arranged for 2027 and we will be launching those dates and titles very shortly on the World Federation's website. We have loads of excellent world-renowned speakers who have agreed to contribute to this seminar series.

[00:03:43] So let's kick it off. And for the next 38 minutes or so, let's think about understanding and explaining attention-deficit/hyperactivity disorder.

[00:03:54] And I think that distinction is really important, because I quite often understand things, but it's not until I have to try and explain them to patients or explain them to my students that I suddenly realise that maybe I don't understand them as well as I should do. So when we are talking about ADHD, and keeping with this idea of a complete return to basics, what are we actually talking about? Because it is a very, very complicated and often controversial diagnosis, and a lot of people don't even really fully understand the core symptoms.

[00:04:34] So when we're talking about ADHD as a disorder in childhood, we're talking about children who struggle with inattention, with impulsivity and with hyperactivity.

[00:04:46] So when we're talking about inattention and children who have difficulties with inattention, we're talking about children who do work that lack attention to detail. Maybe their homework is very disorganised. They have difficulty paying attention, and they find paying attention quite effortful. They would rather do things passively, like watch video clips, rather than do something more active like read a book. They're very poor at finishing tasks, great at starting them, but perhaps poor at finishing them. They have poor organizational skills, they lose things, they're very forgetful, and they're very easily distracted.

[00:05:30] When we're talking about impulsivity, we're talking about children who can't wait their turn before calling out an answer, perhaps in a classroom setting, or they can't wait their turn in a playground setting, or when they're playing a game with other children or adults. And they often interrupt and intrude on other people, which parents can find quite difficult to manage. In terms of hyperactivity,

[00:05:57] children with high levels of hyperactivity fidget quite a lot with hands and feet, body parts or objects in order to manage their hyperactive behaviours when they are still, because they would rather be running around, they leave their seat in the classroom and walk around the classroom, often, perhaps without the teacher's permission. They run and climb excessively on almost everything. They find it very difficult to work or play quietly. They're always on the go, as if they're driven by a motor, and they talk excessively. They'll often say the same thing to you several times over just because they need to talk and perhaps they can't think of something new to say.

[00:06:41] And there's lots of ways of defining ADHD, but one way to do it is to think about it as a neurodevelopmental disorder. And we say neurodevelopmental. The neuro part comes from the fact that the brains of ADHD children are different. Now, we could have a whole seminar on structural and functional differences in the ADHD brain, but we're not necessarily going to do that straight away. But there are structural and functional differences. But I think it's enough for clinicians to know just that the brains are different. And generally the differences in the brains lead to inefficiencies in the way that the child manages their inattention, impulsivity and hyperactivity. Everything works, but it just doesn't work as efficiently as it should do. And because of those inefficiencies that leads to problems with development, so children gain control over attention, managing their impulsive behaviours and managing their hyperactive behaviours at a later date than non-ADHD children.

[00:07:51] Now that doesn't sound too ominous to be honest. Except that we live in a chronological world. In most places around the world, children tend to go to school by a certain age. The age varies a little bit, but here in the UK you have to be legally at school by your 5th birthday, and quite often, because of that, the impact of the ADHD brain on the rate at which children acquire control over their attention, impulsivity and hyperactivity, quite often children aren't ready to go to school, but they have to go to school anyway. So they go to school not having the basic skills that they need in order to thrive when they arrive at school. So they're at school here in the UK, for instance, they're not able to sit still and listen to a story for 10 minutes, or they're not able to wait their turn in the classroom. And those basic skills that they're lacking create immediate educational disadvantage for those children. And that educational disadvantage just gets magnified over time.

[00:09:03] And we are all interested in ADHD for lots of reasons, but one of the reasons that we are most interested in ADHD is that it is a very common psychiatric referral. It's the most common reason for a referral to child and adolescent mental health services here in the UK. And there's a similar pattern in lots of other countries around the world. We're also interested in it because it's a complex disorder. That's why I got interested in research in ADHD, because it was very complex and it's heterogeneous. It's very unusual to meet lots of ADHD children who are all the same. They're all very different. And for clinicians, that is the challenge. Can you identify which children meet diagnostic criteria for ADHD? And once they have a diagnosis, do you know how to help families manage their child's ADHD when everything is so different and heterogeneous?

[00:10:03] And ADHD is also relatively common. Now, diagnostic rates for ADHD are a controversial topic in the United States and in Europe at the moment. But generally, when you look at lots and lots of prevalence studies, you do get differences in prevalence. And some of those differences in prevalence are down to methodology, the way the prevalence studies have been conducted. The prevalence rates for ADHD in childhood vary across most studies between 3 and 5%, and most of them arrive at a prevalence rate of somewhere between 4 and 4.8%. And so if there are 30 or so children in a classroom, which is relatively common, and there may be more children in a classroom wherever you're joining us today, it means that there is every likelihood that there is an ADHD child in most or all classrooms in every school in whichever country you're in today.

[00:11:08] And ADHD is also associated with quite a lot of negative impacts. Now, there are some positives to having ADHD as well, and creativity and outside the box thinking for individuals with ADHD can be very helpful. But generally there are lots of impacts that ADHD has. And one way to summarise them really briefly is from this umbrella review that I helped conduct with some of my colleagues here in Nottingham. And if you're not familiar with the concept of umbrella review, an umbrella review is a systematic review of review papers. And so we surveyed about 130 review papers and we then synthesised all of the findings from those review papers.

[00:11:56] Now, I could spend the rest of the time in this talk just going through that one paper, but I'm not going to. Instead, I'll just say that we identified three overarching themes from that umbrella review. One was the impact of ADHD on physical health. And so, for instance, individuals with ADHD have an increased risk of accidents, higher incidences of eating disorders and obesity, and greater risk of drug and alcohol abuse. So there are quite a lot of impacts of having ADHD on your physical health, and impacts on your mental health. So increased risk of depression, anxiety and suicide, low self-esteem and gender dysphoria, and increased risk-taking, particularly in adolescence. And that might be taking risks riding a bicycle, riding a motorcycle, drug and alcohol experimentation, a whole range of risks. And then there was a third category about the kind of other impacts, including when those individuals are older, increased risks of joblessness and unemployment, interpersonal relationship problems, relationships breaking down, increased risk of divorce, unwanted pregnancy in females with ADHD and peer problems. So difficult social skills, meaning that you have fewer friends and therefore perhaps may feel lonely. And we would not want any individual to experience an increased risk of any of these risks.

[00:13:24] On top of that, ADHD is also a costly disorder. And this is just a schematic from a paper I published in 2019 where we looked at the economic cost of ADHD in adulthood for individuals who were not diagnosed in childhood. And it was a register study based in Denmark, and we had 365 individuals with ADHD and no other comorbid diagnosis, comparing them to their same-sex biological sibling without any diagnosed mental health problem. And we were able to establish the cost for both groups and we subtracted the sibling costs from the ADHD group cost. And this was the cost per individual per year. That's €21,134, that's about 24,000 US dollars per individual per year. So individuals with ADHD cost about 24,000 US dollars more than their siblings per person per year. That's an enormous cost. The costs are spread out. Some of the costs are borne by the state, some of the costs are borne by the individual. But at the end of the day, it's a huge increase in individual cost per person per year for having ADHD.

[00:14:57] And then we move to how we diagnose ADHD. Now Luis Rohde is going to go into this in a lot more detail. These are just a few holding slides to introduce his talk and to encourage you to engage. We know that if you're going to diagnose ADHD using the Diagnostic and Statistical Manual, DSM-5, the individual child has to have a persistent pattern of inattention or hyperactive-impulsive behaviours that interfere with functioning or development. There are nine symptoms of inattention and nine symptoms of hyperactive-impulsive behaviour in DSM-5 ADHD, and the child must have six or more symptoms of inattention or six or more symptoms of hyperactive-impulsive behaviour in order to get a subtype diagnosis. And of course you can also get the combined type, where you present with six or more symptoms of inattention and six or more symptoms of hyperactive-impulsive behaviour. The symptoms have to be inconsistent with developmental level.

[00:16:03] And of course, like for all psychiatric disorders, they have to have impairment. It's not just about having symptoms. You must have high levels of symptoms, but those symptoms must also create difficulties for you. We also need to make sure that you cannot explain the profile of symptoms and impairments in another way, such as a manifestation of oppositional behaviour, defiance or hostility.

[00:16:28] When I used to diagnose, I occasionally would come across children who were really quite deaf, and actually you give them a hearing aid and it turns out they can pay attention really well.

[00:16:38] So once you have got the profile of symptoms and you've ruled out other explanations for it, and you've also worked out that the symptoms are pervasive, which means that they need to occur in two or more settings. And for children, those two or more settings can only be really home and school. For adults, they can be home, school or work. And when we think about making assessments, obviously we make assessments and assess and diagnose slightly differently around the world, because culture plays quite a large part both in the presentation of the disorder, but also in terms of how we make sense of it.

[00:17:18] But we would normally use screening measures, and just as an example of that, there is the Swanson, Nolan and Pelham scale, the SNAP. We should also use a clinical interview, like the Diagnostic Interview Schedule for Children or the Parental Account of Childhood Symptoms. Interviews would be interviews that would help you to make sense of what parents are telling you about the pattern of behaviour that their child has. We should always look at reports from parents and teachers and here in the UK we would send the teachers some questionnaires to fill in. If school reports are available to you, I always find that they do tell you quite a lot over a period of time. Teachers pick up on patterns of behaviour that can be very informative in helping you as a clinician to arrive at the conclusion that an ADHD diagnosis is warranted. We used to do classroom based observation in the past using measures like the Abikoff Classroom Observation Code, and there are other classroom observation schedules. Here in the UK we tend not to do classroom observation anymore because it's very disruptive and it's quite expensive.

[00:18:29] And it's been replaced with a computerised test that is an aid to decision making called the QbTest. And this may not be available in your country, but if it is, it can be very helpful. We did a trial of it to show that it reduced the number of appointments the family needed with the clinician in order to arrive at a diagnosis. And it was very good at ruling out an ADHD diagnosis at an earlier point, which is very helpful because sometimes the family have lots of visits and the conclusion is actually that they don't have ADHD, and they may have autism. And it also, and I think this is quite important, enhanced clinician confidence because quite often when we're making a diagnosis, ADHD is so complicated that you're never quite sure whether it's ADHD or not because it's so complicated. And that makes us hesitant and we might want to see the family again because we're just not sure.

[00:19:28] And one of the interesting things about ADHD is that the symptoms are so very ordinary. And that's quite unusual in psychiatry. For most psychiatric disorders, the symptoms are very extraordinary. If you are hearing voices and those voices are telling you to do something, then you are either having a very religious experience, but in most cases, you're probably not having a religious experience.

[00:19:53] You may be having a psychotic episode. But in ADHD the symptoms are ordinary, and if you took those DSM-5 criteria for ADHD and you applied them to one-and-a-half and two-year-olds, nearly all children would meet diagnostic criteria. But developmentally something incredible happens in the third year of life and children on a trajectory towards non-ADHD development begin to gain control and they begin to calm down and learn to pay attention and inhibit their impulsive behaviours. And children on a developmental trajectory and at risk of ADHD do not; they carry on engaging in those behaviours. And so parents of children with ADHD need things like stair gates for much longer than they might have expected.

[00:20:42] And ADHD, as a behavioural manifestation, and if diagnosed as a disorder, comes with lots of impairments and those impairments are different depending on the age of the child. So in the preschool years, really it's behavioural disturbance that is the greatest impairment. So ADHD children are very non-compliant. They're quite emotionally dysregulated, and they, they just won't do things for parents. And that can be very difficult for parents. When they enter school, and it doesn't matter at what age that is, then they kind of keep the behavioural disturbance, but they're not school-ready. So academic problems emerge from the outset because there's a difference between what the expectations are of the school and what the child is able to do given the impact that ADHD has on their ability to learn. Also, you get early difficulty with social interactions, and that can impact on the child's self-esteem, because they already look at their peers in the classroom who seem to be finding things quite easy, and they're finding things like paying attention or learning to write quite difficult.

[00:21:54] When you move into adolescence, you keep all of the other impairments, but you just keep adding new ones. Academic problems become more manifest, self-esteem issues become more magnified, and then you start experimenting. And the impulsivity and the novelty seeking part of ADHD means that you're much more likely to start experimenting with drugs and alcohol, have accidents, and take lots of risks. And if you are lucky enough to get through schooling and into college age, you keep that academic failure. If you don't go to college, you're trying to get a job and you're finding a job or holding down a job quite difficult. And your ADHD in adulthood also impacts on interpersonal relationships and there are lots of relationship breakdowns, and [inaudible].

[00:22:48] When we look at the symptoms of ADHD over time, longitudinal studies have established that impulsivity and inattention are relatively persistent across development. Hyperactivity is less persistent. So the hyperactivity symptoms, they reduce as the child gets older. They also tend to manifest in other ways. So you might be less hyperactive as an adult, but we do see lots of mind-wandering in adults and this is evident both in clinical samples.

[00:23:33] And so I wanted to say something very briefly about the causes of ADHD because again, this is quite a complicated area. Like most psychiatric disorders, genetics play a very large role in the determination of ADHD. ADHD is a disorder that is approximately 70% genetic. And we know that the genes lead to, or inform, some of the structural and functional differences in the ADHD brain. Now, if something is 70% genetic, then it's also 30% something else. As a psychologist, I call that 30% something else environment.

[00:24:17] And when we look at the heritability estimates for ADHD, that's 70% genetic influence. The heritability estimate tells us that you inherit genetic risk from your parents and grandparents and that explains about 70% of your ADHD. And so if the other 30% is environment, then some people think that that's actually quite a small amount. So sometimes parents, and clinicians as well, think, well, if it's so genetic, you know, other than, you know, changing the genes, which is impossible because it's not a single gene disorder or doing something like giving medication is the only thing that's going to be effective.

[00:25:08] But in reality, how tall we are is even more than 70% genetic. Yet over the last couple of centuries we have been getting much, much taller. And so you can appraise this information in two different ways. On this slide, on one side we've got data for British men going back to 1710, showing their increase in centimetres. On the right, we have got a very small little pre-Christian church that exists quite close to where I grew up in rural Ireland. And when I was a child in the 1970s, I used to always wonder why they made the door so small. And they didn't make the door so small. It's just back in the pre-Christian era, people were really small. That was probably quite a large door, you know, 1,500, 1,800 years ago. And so if something that is so genetically mediated with a heritability estimate of about 80% is open to environmental modification, because we have all gotten taller because of better healthcare and better nutrition, and it's happening all over the world, then that 30% environmental influence for ADHD is actually a window of opportunity. There's a lot that we can do. We just need to work out how we can modify children's environments.

[00:26:28] And so here we have, from around the world, lots of different kinds of environments. And I wanted you to reflect on how they might impact on a child with ADHD. Now, in the top right-hand corner of the screen, you will not recognise that photograph because it is the field behind my house here in Nottinghamshire and my children played in that field when they were young. And yes, they both fell in that lake at some point in their early childhood. And the photograph below this is a favela in Rio de Janeiro in Brazil. And the next photograph is rural South Africa. And in the top left-hand corner, And this picture might be familiar to some: this is downtown Pudong. It's the financial district in the centre of Shanghai. Now, if you had a young child with ADHD, which of these environments do you think would be most forgiving and would allow them to manage their hyperactivity in more detail? I would say that you'd do better in the field behind my house or in rural South Africa than you would do in a crowded favela in Rio de Janeiro or in the centre of Shanghai where there isn't a blade of grass or a park or an open space. And so this helps us to work out how environments might drive the expression of ADHD symptoms. Just to be clear, environments don't cause ADHD; they just might drive more of the expression of ADHD.

[00:27:56] And so we then come to think about what are the things that might link the genes to the behaviours that we see in ADHD. And the thing in the middle are called endophenotypes, things that link the gene to the phenotype, which is the behaviour. And this is a very old study from Edmund Sonuga-Barke, but it's just a study where he had 77 children with ADHD and he did an exhaustive battery of neuropsychological tests, and he got these results. So he was looking to try and see what was the most predominant neurocognitive deficit in children with ADHD, and the answer was, well, lots of different children have different neurocognitive deficits. So out of 77 children, only 16 children had real difficulties with inhibitory control, and 25 children had difficulties with waiting, and 34 children had dominant difficulties with time estimation and time reproduction.

[00:28:59] And so this slide is here to tell us that there are lots of different neurocognitive deficits that underpin ADHD and we need to consider all of them and the way that they might influence the expression of ADHD symptoms. So executive functioning, motivational style, and timing difficulties all do play an important role for the vast majority of children with ADHD.

[00:29:28] And executive functioning consists of higher-order cognitive processes such as planning, working memory, and inhibitory control. And for anybody who works with parents or children with ADHD or directly with children with ADHD, you'll know that a lot of them really struggle with planning. Or parents will tell you stories about their child's poor planning and how maybe their child loses school uniform or school books or lunch bags and how the parents perhaps can't afford to replace them. And that is a real issue for the family and a stressor for that family unit. And quite often parents or grandparents have to do the planning for the child.

[00:30:13] Working memory is really interesting. Our working memory system is the part of our memory system that allows us to remember things for long enough so that we can decide whether or not we're going to remember something. We are inundated with sights and sounds and smells, and we cannot remember them all. Some of them we don't want to remember. If you walk past a garbage truck on a hot summer's day, chances are you're not going to want to remember that because it will smell pretty disgusting. So our working memory system operates almost like a triage system, working out what are the important things we need to remember and what are the unimportant things that can be discarded. One of the many problems with that inefficient ADHD brain is that the working memory capacity for children with ADHD is smaller, and so it gets easily overwhelmed with things that could be remembered. And when it becomes overwhelmed, memories are forgotten before they can be triaged. So whereas non-ADHD children tend to remember strategically, they remember the important things and they discard the unimportant things. ADHD children often remember pseudo-randomly. They will remember things that are irrelevant, and they will forget things that were really important. And it's very important for parents to understand that because it understandably drives them crazy that the child has lost their book bag or something important, but can remember something really trivial that happened a couple of years ago.

[00:31:51] And then we come to inhibitory control, which is the part of your brain that tries to stop you from doing things that you shouldn't do, a little bit like a guardian angel. And again, the inhibitory control system in children with ADHD works well, but it's inefficient. So two children, one with ADHD and one without, might climb up on a really high wall to jump off for fun. And the non-ADHD child's inhibitory control system will say, don't jump off, it's too high. And the ADHD child will jump off. And as they are hurtling to the ground, their inhibitory control system will say, by the way, don't jump off, it's too high. And that child will, you know, maybe break their leg, and then maybe they're a long way from a hospital. And it's a big thing for them, and it's a big thing for their parents or their grandparents. So everything works, but not efficiently enough to be protective for the child.

[00:32:46] And so in terms of modifying environment, poor inhibitory control means you can't modify your response to environmental cues. You're impulsive. Poor working memory means you have lower storage and rehearsal capacity. You're forgetful, you're inattentive. It helps us to link the genes to the endophenotypes, to the behaviours.

[00:33:07] And then we come to perhaps the most interesting thing in ADHD, which is motivation. So we call this attention-deficit/hyperactivity disorder. But it's not always about deficits. Sometimes ADHD individuals are motivated to behave in ways that best suit their needs rather than the needs of other people. And this is the work of Edmund Sonuga-Barke in his delay aversion hypothesis. And essentially what Sonuga-Barke did is, he was doing neuropsychological tests way back in the 80s and early 90s with children with ADHD and non-ADHD controls. And he noticed that depending on how you varied or manipulated the experimental condition, you could get ADHD children behaving in very different ways to controls or in exactly the same way as controls. And the key thing seems to be whether or not acting impulsively got them through the experiment quicker.

[00:34:05] And so in the standard condition, they were doing a series of trials, it was very boring. And children had to, you know, make choices. And if they responded really quickly, they got on to the next trial, and so they got through the boring experiment really quickly. So they responded really quickly. So you can see here the difference in response time between controls and ADHD individuals, ADHD individuals being much, much quicker in response. And that would be great except they were making lots of mistakes. If ADHD children were fast and accurate, they would rule the world. But they're fast and inaccurate. And what Sonuga-Barke did in this revised condition is that he put a period of waiting after each trial. So each trial now had a fixed length, I think it was maybe 5 or 10 seconds. And when acting early doesn't allow you to avoid waiting or get you through the experimental condition quickly, ADHD children look at the experiment, and they make exactly the same choices as non-ADHD children. So in the standard condition they're much quicker and much less accurate. And in the revised condition where acting early doesn't help them, they're exactly the same. And that was a really, really unique perspective on ADHD. And it led to the development of the delay aversion hypothesis, which says that ADHD children find waiting not just unpleasant, but actually aversive, and they will always seek to avoid having to wait.

[00:35:39] And we understand that a little bit more for children in different conditions where they have some influence or where they have very little influence. So where they have some influence over their environment, where they have a choice, and they experience waiting, ADHD children will usually seek to minimize delay, which looks impulsive. So an ADHD child may have looked forward to playing football all week with their friends. They go out to kick the ball around. Nobody's kicking the ball to them. They're getting bored, they're waiting. And they think, I hate football, I hate my friends, and they leave. But to all of the friends, that looks like a really impulsive decision. But actually to the ADHD child, it was a strategic decision because avoiding the waiting is better for them than enduring the waiting and keeping playing the football.

[00:36:29] If you take that same child and you put them in an environment where they have no choice, and you can put them in a classroom in almost any country in the world, they can't run out of the classroom, or they know they will be severely punished for running out of the classroom. And most ADHD children are quite reasonable in my experience. They can't minimise delay. They have to maximise non-temporal stimulation. They have to distract themselves in the passing of time. So they daydream, they become inattentive, they think about what they're going to have for lunch, they think about what they're going to do when they go home, but they're not paying attention to what's going on in the classroom. Or they become overactive, they get up and walk around the classroom, or they fidget to try and distract themselves in the passing of time. And if neither of those things work, they start interfering with other children. And then the other children complain to the teacher, and then the teacher gets really cross. And that passes loads of time. And if that ADHD child is really lucky, that teacher will get so cross, they'll send the child out of the classroom because that's exactly what they wanted to happen in the first place.

[00:37:34] And then lastly we come to timing, which in my experience is the thing that most people don't know much about, but actually ADHD children really struggle with time estimation and time reproduction. And even at a really early age there are very simple experiments, say involving something like a light bulb and it lights up for intervals of time. And when the light bulb goes out, the child just holds down the space bar to see how long the light was lit for. Non-ADHD children are surprisingly good at this task if you keep the time intervals relatively short. ADHD children find it really difficult. It's a very, very discriminating task. So we know that ADHD children can't estimate or reproduce time, but they live in a world where everybody talks in the language of time and it's a language that they do not understand.

[00:38:23] And then lastly, and I am going to keep to time because I've just been talking about time, but I also have an excellent chair who I know will keep me to time. Lastly, I want to come to the power of reinforcement. ADHD children on average need five times the amount of reward and reinforcement of non-ADHD children. Yet they receive very little. And lots of parents will tell you, I'd praise them if they did anything that was worth praising. But they don't. So they do lots of things that warrant my criticism, but very little that warrants my praise or my reward.

[00:38:58] Yet ADHD children are desperate for praise and reward and I wanted to share this study with you from Elizabeth Liddle, who I used to work with when I was at the University of Nottingham. And it's an incredible study. So what Liddle and her colleagues were doing is they were putting children with ADHD into an fMRI scanner to do tasks, and they were doing that under various different conditions. It was a very, very sophisticated study. So they were testing children on and off ADHD stimulant medication, and at high and low levels of reinforcement. And the reinforcement in this condition was points. And the child could exchange points for prizes, toys. And before they started the experiment, they went into a little shop and they could see what all of the prizes were. And each prize had a price tag with a number of points. So if a child liked a particular prize, they knew how many points they had to get in order to be able to walk out with that prize at the end of the study. And so they went into the scanner on and off medication, doing tasks in the scanner and either receiving small amounts of points for those tasks or high amounts of points. And the results of the Liddle et al. study were, I think, really, really important because what she found was that when ADHD children were off their stimulant medication but doing tasks at high levels of reinforcement, their level of cognitive control, in this case, it was all about default mode network activation. But their level of cognitive control was the same as when they were on medication at low levels of reward.

[00:40:52] Now, some parents don't want to medicate their children. You may be joining us from countries where it's quite hard to access medication. But imagine if parents understood that high levels of reward and reinforcement and praise and acknowledgement could have the same cognitive effects in terms of cognitive control as medication. Now, that doesn't extend to all behavioural control, but it at least extends to cognitive control. And it just reminds me of a wonderful high-quality experimental study about how important something like praise, reward and recognition is. And in this particular study, the reward was points, but we know that ADHD children actually have a preference for social reward. So acknowledgement, praise, telling them they've done well, capturing the good, all of those things can have a profound effect on ADHD children and the management of their behaviour. And they are free.

[00:41:57] So in summary, what we've been talking about in this very first webinar from the World Federation of ADHD, we've been talking about children with ADHD who present with inattention, impulsivity and hyperactivity. We've mentioned that ADHD is associated with a wide range of impacts and impairments, that it has a high economic cost, that some symptoms of ADHD are very common, but the cluster of six or more is not. And while ADHD symptoms are highly genetic, the environment is also extremely important. We've talked about what drives the expression of ADHD symptoms in children, in particular, that aspects of executive functioning and having to wait, and delay aversion, and not understanding time, can all help explain why children with ADHD might behave in the way that they do. And that praise and reinforcement can be extremely helpful, and it can also be provided by parents and teachers at absolutely no cost, which I think is really important.

[00:43:06] Thank you very much for listening, and I'm looking forward to going over to the chat to see what sort of questions that you've asked.

Jan Buitelaar

[00:43:14] Thank you very much, Dave. This was a wonderful lecture.

David Daley received his B.A (Hons). in Applied Psychology with Sociology from the National University of Ireland, University College Cork, Ireland and his Ph.D. in Developmental Psychopathology from the University of Southampton, UK.  After time spent as an assistant Professor within the School of Psychology at the University of Southampton, and assistant and associate professor on the North Wales Clinical Psychology Doctoral Programme at Bangor University, he was appointed Professor of Psychological Intervention and Behaviour Change in the Division of Psychiatry School of Medicine, University of Nottingham in 2010. From July 2022 until July 2026, he was Head of Applied Psychological Practice at Nottingham Trent University, where he is now Professor of Psychological Intervention and Knowledge Exchange. David is also a member of NHS England’s Experts in Evidence ADHD taskforce, a member of the European Network on Hyperkinetic Disorders EUNETHYDIS, ADHD Guidelines Group and Co-chairs both the education and dissemination committees for the World Federation of ADHD. He is also international lead for the New Forest Parenting Programme.

David’s research interests are focused on non-shared environmental influences on child and adolescent development within the context of neurodiversity. In particular, he has devoted much of his career to the study of factors that enhance and interfere with the effective and enjoyable parenting of children with ADHD. He is also internationally recognised as an expert in environmental modification for neurodiversity.