Professor Samuele Cortese Hello, everyone.  My name is Samuele Cortese. I am currently   an NIHR Research Professor, a Professor  of Child Adolescent Psychiatry at the   University of Southampton in the UK and, also,  a Professor of Child Neuropsychiatry at the   University of Bari in Italy and Adjunct  Professor with NYU in the United States. In this presentation, I will discuss  the data regarding the “Prevalence of   ADHD,” and I think it’s important  to look at the recent evidence,   because I believe, when we discuss with  colleagues, we can hear and, you know,   have in mind different figures in terms of the  prevalence. Some they will say around 2%, other   5%, some other, they will say around 10%,  and, of course, knowing the evidence on the   prevalence of this condition is important,  because this has important implications in   terms of the organisation of service and the  delivery of care for these individuals. Right,   so, before starting, I will briefly show my  conflict of interest, and that you can see here. And, now, let’s move to the current presentation  slide. So, what – mainly what I will discuss   are the key findings from this paper. You’ll  see here the first page of the paper that my   team published recently, last year, and it was  really, I guess, a comprehensive analysis of   the literature on the prevalence of ADHD.  So, actually, this is an analysis of the   data from the so-called “GBD, the Global Burden  of Disease,” and many of you may be familiar with   this study. It’s an important study, a series  of studies, actually, that is very influential   in establishing the prevalence, the incidence,  and the burden of many conditions in healthcare. Right, so, the aim of that paper that we  published was to then present the incidence,   the prevalence and, also, the burden of  ADHD, by country and region, and by sex,   across each year in the period 1990 to 2019,  this was where the data were available for,   as estimated, as I mentioned, by  the GBD. And, also, importantly,   while we were analysing and appraising this  data that we have not collected ourselves, we   relied on data already available from the GBD, we  came to the conclusion that possibly the GBD may   have presented some pre – data on prevalence that  were somehow misleading, So, we have recalculated,   we have reanalysed ourselves the data from the  GBD to make sure that we could provide the readers   with reliable figures on the prevalence and the  incidence and the global burden of disease of   ADHD, but, today in this presentation,  I will focus mainly on the prevalence. Right, so, to provide more context on the GBD,  and we used the data from the GBD 2019, these are   data that come from 204 countries and territories,  so different regions around the world. And these   are data that have been collected based on a very  rigorous systematic review of different databases,   and including studies based on service,  using probability sampling. And the way   ADHD was diagnosed in the studies included  in the GBD was based according to the DSM,   from the third to the fifth version, or the  ICD, including the nine and ten version. Right, so, as I mentioned, we didn’t only present  the data from the GBD, but we reanalysed this   data, because we thought that there was some  methodological issues. And the main methodological   concern is around the fact that the GBD pulled  data from many countries around the world, but   not in all of these countries data were  available. So, when data were not available for   some countries, the GBD used some imputation,  some statistical and mathematical methods,   to in a way provide – to come with a figure,  even if data had not been collected actually   in these countries, and we think that this may be  problematic, because it may introduce some bias. So, what we did was that we reanalysed and we  included data only from those countries for which   actual data on prevalence were available. And we  limited this to data up to 2013, to be – in order   to be able to compare our findings with another  meta-analysis that we knew was of high quality.   And we conducted then a meta-analysis, so, a  quantitative synthesis, where we pulled this data   from all the studies, and we also ran what is  called a ‘meta-regression’, which is a particular   approach which allow us to assess the impact  on variables, key variables, on the results.  Right, so, what we found was the following.  So, according to the GBD data, so, including,   also, countries without actual data, so  country where the prevalence was imputed,   and the GBD included a total of 84 million people  with ADHD, globally, and this gave a prevalence,   age-standardised prevalence of 1.13,  as you can see here in the slides. So,   actually, this is a quite a low figure  compared to what we usually hear   about ADHD prevalence, and I  will comment on this in a second. The incidence was 4.2 million globally and the  age-standardised incidence was 0.061%. Now,   again, according to the GBD data, the raw  prevalence has slightly increased from   2000 – in the past 20 years, basically, while  the age-standardised prevalence has slightly   decreased, but may – we can say that figures  have been consistent and constant over time. The incidence likewise has slightly  increased, in terms of raw incidence,   and has slightly decreased in times of  age-standardised incidence. Interestingly,   both the prevalence and incidence were between 2.5  and 2.6 times higher in males compared to females,   during the past three decades, according  to the data of the GBD. You can see here   in red the plot for the females  and in blue the plot for males. Now, another result from the GBD was that  the incidence peaked at the age of – between   five and nine and the prevalence peaked  between the age of ten and 14 years. Now,   what we found was that when we restricted  analysis to the countries for which actually   data were available, we found a pooled prevalence  of 5.4%, which is very similar to the prevalence   provide in another good and rigorous meta-analysis  conducted by colleagues in Brazil and published   in 2013. And so, basically, this figure,  which we think is the most appropriate one,   is more than twofold compared the one provided by  GBD. And, once again, highlight the fact that this   figure referred to the pooled prevalence  across different countries in the world. So, I guess that when we are discussing data on  the prevalence of ADHD, probably we should have   a figure of around 5% in mind, which is probably  the prevalence which reflect actually good data,   good quality data. Importantly, we found no  significant differences in the prevalence   of ADHD between low and middle income  countries and high income countries. We   may think that there could be a difference.  Actually, we didn’t find any significant   difference and, also, we found that the  socioeconomic status did not significantly   impact on the prevalence of ADHD in the  meta-regression analysis that we conducted. All the data that I presented so far are related  to children and young people, what about the   prevalence of ADHD in adults? Now, there’s been a  good meta-analysis published last year, pointing   to a pooled prevalence, so, once again, prevalence  pooled across all countries, across all data   available, of around 2.5%. However, it is also  important to highlight, when it comes to adults,   one thing is the prevalence of ADHD according  to the formal criteria, and another thing is   the prevalence of impairing symptoms, which  probably is more relevant, because, arguably,   the current criteria are not well suited to  be used in adults, so we – this meta-analysis,   for instance, relied on criteria  which may change over time. So, I’d like to show this graph from a study  from my colleague and friend Steve Faraone and   his group, showing that if we consider a group  of children with ADHD diagnosed in childhood   around the age of five or six,  and we follow them over time,   only 15% will maintain the formal diagnosis  of ADHD at the age of 25. However,   among these actually around 65% will present  symptoms which leads to a functional impairment,   even if they don’t meet all the formal criteria  for a diagnosis, and, actually, up to 71% will   present symptoms, impairing symptoms, once  again, without formal diagnostic criteria. So,   when it comes to a diagnosis in adults, it’s very  important to look not just at the formal criteria,   but, also, the impairment that  these symptoms are associated with. I think that was everything for this  presentation. Thank you very much.