Deficient Attention and Disordered Activity: Child Psychiatry's Response to ADHD.
By Nick Child
Faced with an overwhelming problem of numbers of referrals for ADHD (Attention Deficit / Hyperactivity Disorder), the Scottish Child and Adolescent Psychiatry Section of the Royal College of Psychiatrists arranged a day on the subject (16th November 2001) and got me to do my alternative bit. Below is the later published version (PDF here) in Clinical Child Psychology and Psychiatry (2003), 8, 167-178. It is reproduced here by permission of Sage Publications, Thousand Oaks, London and New Delhi from the editor of CCPP. Copyright is with Sage Publications Ltd 2003, website http://www.sagepub.co.uk.
ABSTRACT
Because attention deficit hyperactivity disorder (ADHD) seems to be a simple medical diagnosis with an unusually effective medical treatment, nothing before has attracted so much business for child psychiatry. Like any business that booms when it is not ready, child psychiatry risks going bust. This is an analysis to inform our urgent business planning in a UK context.
KEYWORDS
attention deficit hyperactivity disorder (ADHD), child psychiatry
In the world of business it is known that the commonest cause of going bust is not getting too little work. Companies collapse when business booms before they are ready. For child psychiatry in the UK, if not elsewhere, attention deficit hyperactivity disorder (ADHD) was not part of our business plan, so our own attention has been deficient. Despite our supposed science and acumen, we have failed to pay attention to the very obvious logic of where our child psychiatry and ADHD business was leading. Rightly, we were pushed by Diagnostic and Statistical Manual (DSM) countries and the media to take ADHD more seriously than we did. Who needs a better advertising campaign? Now many of us face an avalanche of ADHD cases, at which we are trying to shovel with ADHD clinics and various official guidelines on ADHD (eg Scottish Intercollegiate Guidelines Network [SIGN], 2001). But, on their own, these loud announcements invite further avalanches on avalanches of ADHD business, inducing disordered overactivity as surely as rescuers at the scene of a real avalanche yelling for victims through megaphones.
The following analysis of the ADHD problem should be nothing new to this readership. Neither should the solution, which I suggest is simply to put into practice the basic Child and Adolescent Mental Health Service (CAMHS) methods and values we all sign up to. These seem to have worked well enough over several years in the small Tier 3 CAMHS team where I work. ('Tiers' are tiers of welfare state-based CAMHS in the UK, with Tier 1 being primary care and Tier 4 the regional specialist services in the centres of excellence.)
First I must confirm my greatest respect for the medical model in the right place (Child, 2000). Indeed the lesson here is drawn straight from a medical bible. Sophisticated neurodevelopmental thinking and research on core ADHD and other developmental disorders are an essential and valuable part of child psychiatry. There is no question that there is a primary biological core to some ADHD, and no question that prescribing medication can be extremely helpful. But there is also no doubt that there are differences in diagnostic and clinical practice between CAMHS in different areas and centres.
ADHD highlights the old 'ivory tower' syndrome - in some cases the 'on a different planet' syndrome - raising the question of how far academic child psychiatry is of use to ordinary community child psychiatry. For sure, the knowledge, skills and training in child psychiatry have become progressively better over the years. When we refer difficult cases into the centres from our peripheries of excellence, then the very highest of textbook child psychiatry is what we need. As I have noted before (Child, 1991), someone has got to do that onerous collection of jobs in the centres so the rest of us can gratefully lead more normal lives.
My own contribution to the field has equally been in developing the theory and practice of community child psychiatry. The evidence base here is theoretical and practical. My theoretical thinking has been published and has not been contradicted (eg Child, 2000; Gustafsson et al., 2001). It has not been accepted either, but that was predictable for the reasons given there. Locally published documents include the Motherwell (Child, 1996) and the Lanarkshire ADHD Guidelines (Child, 2002), always being redrafted of course, and descriptions of the service and its philosophy.
The practical evidence base is in the anecdotal audit of how we work things in our patch. In particular, we welcome our task as the key service provider for ADHD assessment and treatment, including medication, and we do have more ADHD referrals than before. But we have nothing like an avalanche to deal with. ADHD takes its place as a small part of our normal workload. From the cases that have been systematically returned to us from outside the area and from Tier 4 services, there now seem to be few dissatisfied ADHD refugees from our particular team's area. Having set up our ADHD approach in 1995 in local interagency discussions, we do not spend a lot of time in hassles with families or other agencies. General practitioners (GPs) have been happy to prescribe to the few at our request, and to continue monitoring as part of a shared care arrangement. Shared care with GPs may become more of a problem in future as the implications of potentially long-term prescription sink in.
How do we do it? I am going to use an organizational management analysis starting from a medical-model logic. Ethical and philosophical arguments are elsewhere (Child 2000).
Figure 1 shows a simple population prevalence balloon: 100% population, a quarter with a broad condition needing help, and a smaller core group needing special help. A third may worry that they have got it. With the same finite service resources, it is clear that the help needs to be targeted to the right sized group. Figure 2 shows a service 'balloon' that 'flies' and one that 'crashes'. Before fitting ADHD to these diagrams and to free our thinking up, let us try out another example. Suspend ADHD parallels for now.
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The Terror Bug Example
I take the classically medical example of fever - fever from a newly feared source, terrorist-induced infection. This is an international academic journal, and I deny any nationalistic, metaphorical or other moral judgement by this example. Imagine that a terrorist organization launched a new fatal-if-not-hospitalised infection on us with no test to identify it. Unnamed at first, the media might call it the Terror Bug. To manage it, you would have to use a broad over-inclusive identifier, such as having a temperature. You would likely have to admit everyone who had a fever to hospital in case they had the Terror Bug. Hospitals would go completely bust from this boom in their business. Their 'balloon' would crash. Obviously, you would look for something that narrowed identification - say a specified high temperature. Or better still, develop a test that would specifically show up the bug. Then the 'balloon' could 'fly'.
Note that others with other kinds of fever, when you can tell them apart, may need help and treatment too. But that could be done without hospital admission, and it could be done by other agencies. Indeed commonly, fever, a very biological condition, is taken care of by the sufferer and their own family without the need for any professional services at all, just bed rest and a Paracetamol or two. Note that, in a non-welfare state system such as the USA, where DSM and ADHD were developed, the only way to get funding for treatment may be through a formal medical label, even if in this example it would be 'fever of unknown origin'.
At least with fever you have a thermometer as a measure for separating those who were only hot under the collar with fear that they have a temperature from those that really do. As long as people are not stirring their tea with it, the thermometer is objective. Anyway, people actively do not want to have a fever. They are pleased when the doctor announces that their temperature is normal, that they are well. Especially for the Terror Bug without a specific test and with media publicity, there will be an expansion of demand because of people who worry they have got it. So a number of those who do not have the Terror Bug will want to be seen too, reminding us that it is a doctor's job to diagnose health, the absence of disease, as well as its presence and the limits of what the diagnoses can explain (Smith, 2002). But the thermometer will easily reassure them since worry does not cause fever.
To repeat that last paragraph with the ADHD parallels added: As long as people are not stirring their tea with it, the thermometer is objective. (Less so the parental scales for ADHD that openly invite families to stir and heat their tea with them!) Anyway, people actively do not want to have a fever. They are pleased when the doctor announces that their temperature is normal, that they are well. (Unlike many ADHD seekers.) Especially for the Terror Bug without a specific test and with media publicity, there will be an expansion of demand because of people who worry they have got it. (Like ADHD.) So a number of those who do not have it will want to be seen too. (Like ADHD.) This reminds us that it is a doctor's job to diagnose health - the absence of disease - as well as its presence. (How well do we do that in child psychiatry with a disease-like label for anything that moves?) But the thermometer will easily reassure them as worry does not cause fever. (Unlike the scales which can generate worry and loss of carers' confidence around ADHD.)
Once the Terror Bug can be specifically diagnosed and treatment identified, then it may be that treatment will be done by GPs or even available over the counter like pregnancy tests and Paracetamol. Maybe, to move to a child psychiatry example, enuresis (bed-wetting) went like that. With its medical label, with pads and buzzers or medication, it is now dealt with mainly by others in more frontline tiers, such as community paediatricians, and of course parents can buy their own pad and buzzer. Any skills that child psychiatrists created have been taught and transferred downwards. But is our ADHD expertise transferable and what are the dangers? The comparison of ADHD and enuresis can be taken further in this respect, because bed-wetting too is a developmental problem and sometimes has wider associations of, for example, psychological stress and sexual abuse. The key difference is in the perceived chance of permanency of ADHD, though this is arguably not greater than for enuresis. It is the more pervasive effects of the ADHD label and treatment that loads the issue. For now I will stick with the Terror Bug and ADHD.
ADHD Rationale
A number of issues arise from the comparison of the Terror Bug and ADHD, which our deficient attention may have missed.
Transfer of Specialist Skills
One way of looking at services for ADHD is to define the necessary skills for making the definitive assessment, clarifying the conditions and qualifications required for that task. This perfectly valid aim has been one main purpose of official guidelines (e.g. SIGN, 2001). For fever we have transferred down the originally specialist technology of thermometer and drugs. It will become apparent that in one way, for ADHD, I would transfer nothing down; in another way, I would transfer a lot.
Biological or psychosocial? Unifactorial or multifactorial?
Even the most core case of ADHD is never as biological or unifactorial as fever. For example, one mother had read up on ADHD and I agreed with her that methylphenidate was appropriate, despite a difficult and complex wider picture. And the medication worked where other approaches had not got far. Unusually, however, she was quite clear that the cause of the ADHD was the way she had brought her son up in his early years.
Caseness and prevalence - Core and broad?
Often ADHD is presented as if it was as simple as fever. Diagnose it by taking the temperature with a scale (popular version provided in your Daily News), then get the wonder drug prescribed. Scales may have their uses, but they are certainly not as objective or scientific in identifying caseness at broad or core levels as thermometers can be. In my diagrams, the 25% estimate for the prevalence of children who, by their scores on simple questionnaires alone, could fall in the broad group is not an exaggeration (see Szatmari, Offord, & Boyle, 1989). But I hope my guestimate of 33% of all children is hyperbolic for the extra families who might worry that their child has ADHD.
Effects of worry? Media promotion?
Worry for ADHD can itself exacerbate the problem, removing confidence and distracting from more effective functioning. That is what successful media promotion and advertising campaigns do: you never knew you needed designer sportswear until they told you. Even if you cut my estimates to a fraction, the argument still holds.
Broad test?
If a defining measure is what you think is needed for the broad group, then scales and DSM probably provide the best test there is. Defining that group might be essential in an insurance based market (e.g. USA) where help is not otherwise available. For the UK, this model is unnecessary because the welfare state provides help without the requirement of labels and because the US-type model may lead us to services that evidently can crash. So, narrowing down what Tier 3 CAMHS can offer is even more essential to avoid more closed waiting lists and overstretched, ground-down services. Particularly if ADHD is seen to be a child psychiatrist's job, we are simply never going to be resourced to see that many children.
Core test?
If there was a suitable core test, for example, a ready test for some gene for the biological factor that would lead us toward readier prescription for those cases, then for them, it would be much simpler. We may then also have gone a long way to separating out the 2% core from the broader 33% and the labels would reflect that greater discrimination. In case it is needed, I note that ordinary brain scan-type evidence would not be a useful test as an indication for medication, since many ordinary human activities cause brain function to heat up and cool down. Of course, ordinary chemicals alter it too and that is also not necessarily a reason to (over) use chemicals as a cure.
The nearest we have to a suitable core definition, quietly and strategically mixing up ICD and DSM, as the Scottish SIGN Guidelines title and content do, for exmaple, is the use of the tighter DSM Combined ADHD category. Basically, we are recasting our old ICD category for hyperkinetic disorder. Hill and Cameron (1999) and SIGN (2001) deepen this surface description into one for a 'primary disorder of hyperactivity'. Taking the criteria a bit further than they do, this is when a child's inattentive, impulsive restlessness is extreme compared with developmental norms, impairing development and other functioning, pervasive across situations (home, school and clinic), pervasive through time (i.e. more than 6 months), present from and beyond pre-school years (i.e. not generally considered in under five-year-olds), and not accounted for by other diagnostic conditions or circumstances.
Organising and authorising resources
If such a definition is properly understood and used by GPs and all agencies involved, it will certainly help select the 2% ADHD that need more of the medical or other intensive specialist involvement, from the 23-31% that may not, in the same way that the distinguishing high temperature helped narrow down on the Terror Bug. If this definition is drilled home it will be an important lever. Until then, anything we say about ADHD will be taken and used more broadly than we would want, to create the avalanche that tests the organization and authorization of resources.
Other tiers? Other agencies?
I presume no one wants to see thousands of children officially labelled and on medication for years. This may well happen, as it has for psychotropic medication with adults, if it is simply left to GPs and paediatricians facing parents flourishing an evidence base of Daily News clippings and Internet printouts. So where there is concern enough to consider the ADHD diagnosis with a view to starting medication, then that should be done by the multidisciplinary and co-ordinated multiagency approach characteristically provided by our UK Tier 3 CAMHS. I am not convinced that any paediatricians, unless fully experienced and supported in CAMHS work - that is doubly trained and practising - will ever have the necessary time and skills to properly identify and separate out all the factors for the assessment and management of ADHD cases. And it just will not do for us, or anybody, to just try methylphenidate first on the basis of a surface description to see if anything more is then needed.
There are many symptomatic treatments that are used like this in medicine and psychiatry, but this step, once it is made with ADHD, is much more difficult to recover from given the biological and 'lifelong' view that is currently dominant. However, as our practice matures and becomes less polarized, we can expect a more moderate use of medication, as in the similar pattern used for treating adult depression. There, medication is nowadays seen to be one definitely time-limited aspect of helping the symptom, pending the more lasting effects of psychosocial methods.
More problematically, I have serious reservations about specialist ADHD Tier 4 CAMHS doing an assessment either. Small Tier 3 services are not perfectly placed, but they are better placed than Tier 4. It takes massive efforts for Tier 4, or anyone even further away, to do proper multifactorial, multi-agency assessment and management from that distance, even if there is core ADHD in the middle of it. Many of us will have examples of this from cases coming into our area having been plainly misdiagnosed and started on medication elsewhere.
If you are running your services right, referrals to Tier 3 are not simple. There is the usual mix of multifactorial causes of CAMH problems all needing to be addressed. Many of these factors will be identified and worked on by Tiers 1 and 2. Where I have qualms about other tiers and agencies wielding the ADHD label and pills, I have no qualms if they are simply doing what they are good at. That is, identifying and helping with the various other ordinary needs and factors that go with the broad ADHD picture and merit it - parenting, childcare and child protection, social and family stresses, medical conditions, conduct and behavioural management, school stresses, peer group, substance use, developmental and learning disabilities, and so on. For ADHD as or for any CAMH problems, that is what multifactorial, multidisciplinary and multi-agency means.
Labels: Ordinary or mystifying?
This multifactorial multi-agency working is best aided by not obscuring and mystifying things with unnecessary, medical, technological or specialist-sounding labels. Why encourage an ADHD framework and pathway when there is nothing at all different in the good practice recommended for ADHD than for any other CAMH problem - except for the magic label and pill at the end? Why not encourage the various factors to be immediately addressed by the more frontline agencies, not sent all round the houses first, sitting on waiting lists, then collecting the label that covers up our pontification about multifactorial this and that, and leads us to appear to boss other agencies around to do what they could have just got on with in the first place?! It is annoying to be nagged to do something that you are already doing or about to do - especially if you are actually the more expert in it, or the one who would have to do it anyway.
'Surely this picture is not true?!' child psychiatrists may protest. But, for example, the Scottish Executive's report and action plan For Scotland's Children: Better Integrated Children's Services (2001), with its extensive crosscutting remit that had them talking to anyone and everyone about everything, says (p98):
The Action Team found a general consensus among mental health professionals that the increased diagnosis of ADHD was as a consequence of improved sensitivity to the condition. However, a few dissenting voices among the specialists were more in tune with the more sceptical attitude found more generally. Many of those working with children expressed concern that (what) was now being labelled in a different way made approaches other than medication unavailable. . . . The Action Team believes that no medical / psychiatric diagnosis should remove a child from the potential assistance available within the range of multidisciplinary children's services.
This is likely to be found elsewhere than Scotland too. So child psychiatry's claim to expertise in multifactorial approaches, in interpersonal communication and in interagency working looks decidedly shaky here. Here too is a simple explanation for why academic child psychiatry is problematic for clinicians who want to work more positively with other agencies in the community as we all claim to do. Unfortunately there are blind-spots in our bioscientific thinking that explicitly exclude this kind of blindingly obvious but not double-blindable evidence from our evidence-based practice and official guidelines.
Label: Over inclusive? Self-help? Welfare state context
Going with this multi-agency approach, you can also better differentiate core and broad ADHD. You can dismantle the ADHD over-inclusive category itself. Instead of 'ADHD' you can talk of children who 'cannot pay attention or sit still' or have, say, 'problems with attention and activity', without those inappropriately medically colonizing capital letters. Ordinary words facilitate some of the help these children, core and broad, and their families need, much of which is in their own hands. That is, ordinary parenting self-help, and help that is available nearby and through doors that are not marked 'ADHD'. In the UK with its welfare state, when referrals of concerning cases are made to Tier 3, they can be welcomed even (or especially!) if not couched in 'ADHD' terms. Our services needed an outside push a few years ago, but nowadays we will think of ADHD where necessary without that.
For those that are referred to Tier 3, a clear pathway helps. In the UK this is probably best through Tier 2 and community paediatricians as key co-ordinators - co-ordinators not of diagnosis and treatment, but of checking that all other relevant aspects have been addressed adequately at more frontline levels before using the 'primary disorder of hyperactivity' criteria to make the 'ADHD' referral to Tier 3. In fact, once that channel is in place, it is likely to be quicker to get to Tier 3 if people refer with an ordinary description of problems and concerns, without mentioning ADHD. So without wishing to return to old-fashioned paternalism, front-line agencies can help families usefully return to the old pre-media, pre-Internet pattern, where patients described their troubles and then professionals diagnosed and helped them, instead of the media-given pre-diagnosis and counterproductive worry.
At present, in the broadest undifferentiated sense, a large group of children have indeed got ADHD. Given the over-inclusive term, and the lack of tests and definitions, those parents will think their child has it in the narrow sense. Running a special ADHD clinic and promoting official ADHD guidelines on their own, helps perpetuate the medical model, the mystique and the misunderstanding. Hence the avalanche.
Desire for the condition? Diagnosing health too?
The large number of families with an ADHD ticket may well need help from somewhere. Why else would we, uniquely, in child psychiatry, see this often furiously positive parental desire for their child to suffer from a condition (Smith, 2002)? It is because illness is the language of degree of suffering. The suffering is worse than having a medical illness. So families would prefer the disease label and all the different kinds of relief that they imagine go with it. So when we talk about the absence of medical illness, and diagnose health, we are not saying that it is nothing, go away, you don't need help. And Tier 3 CAMHS may still be the right place for that help on grounds other than ADHD.
Specialist or generalist?
It follows that there is no reason for there to be a special ADHD clinic. 'Avalanche' control is the usual reason for this approach. But counterproductively, on their own special clinics can attract an increased workload. There is no other reason for them either. We do not have special clinics for most of the many other types of cases we see. Families often push ADHD because they think that the label is what will get them the help they desperately want. But it is my impression that specialist CAMHS actually fail some families by trundling them down the ADHD track, where we do not necessarily think about all the multifactors we would be thinking of if they came through our usual front door. Certainly, an isolated scale-based assessment and a 20-minute medication check-up a couple of times a year are not going to pick up other important and relevant issues of concern in the child and family's life.
Finally, a point about the inappropriate directions for a medical model in the official ADHD guidelines. They advise clearly against seeing children individually because there is no evidence that such an approach 'works'. Taking the ultimate biological disorder, death, I hope I die before there are clinical guidelines for the management of the dying. Even though talking will not 'work' in reducing mortality, I would really like someone to do it with me then.
Key Points for CAMHS and ADHD
Official medical evidence-based guidelines are not allowed to include the wider interagency organization and dynamics. Though equally powerful, the findings of social science and organizational sense fail the hard criteria of medical bioscience. So parallel interagency guidelines are necessary alongside the clinical ones. That is what we did locally (Child, 1996). Here are some of the key points in the approach, most of which are standard recommended practice for all CAMHS.
- Positively welcome, learn about, and lead the ADHD task.
- Pay early attention to quality thinking, talking and planning of services (Child, 1991).
- Discuss and agree local interagency guidelines, incorporating the principles outlined here.
- Help distinguish the core picture of ADHD from the broad one by using ordinary language as much as possible instead. Of course it is a continuum, but somehow we must stop using the term ADHD for both core and broad groups.
- Dismantle ADHD (especially broad ADHD) into its ordinary component multiple factors.
- Authorize and enable frontline agencies, including parents, to do what they already do well with those factors. Health visitors, teachers, social workers and others can all have a go at these.
- Provide ready access to discussion with specialist CAMHS if frontline agencies feel unsure or wonder about more specialist referral.
- Do all you can to ensure that a family gets helped promptly by someone at Tiers 1 and 2 and they will not get to the point of thinking of ADHD and then need Tier 3.
- Whether it is likely to be core or broad ADHD, it is important that childcare and child-protection factors are reliably attended to. Overlooking attachment difficulties and child-care issues is arguably a greater danger in diagnosing ADHD than that of the medication. The message of the label and the pill can be to invalidate further, and shut up, an already oppressed child.
- Realize CAMHS principles in general and in practice. 'Realize' means really do them, not just put them in documents that sit on shelves. 'Realize' means going past defensive professional roles to effective interpersonal teamwork (Child 2001). That is difficult. None of us does it very well, but much of our child psychiatry terminology makes it even more difficult.
- Good CAMHS principles include: skilled and integrated multifactorial, multidisciplinary and multimodal work; effective multi-agency working in general and particular; and responsive CAMH services, phone calls, and consultations.
- Develop clear referral channels and roles. A clear Tier 2 co-ordinating role for Community Paediatricians linking to Tier 3 has been a more recent addition to our local guidelines.
- Within Tier 3, do not set up special ADHD clinics or special waiting lists or separate procedures for such referrals.
- Work with regional Tier 4 CAMHS for second opinions, or cases will go even further away.
- Use the official guidelines for core ADHD whose recommendations include: key diagnostic and prescribing responsibilities with Tier 3 CAMHS; use of the 'primary disorder of hyperactivity' definition; and use of shared care arrangements with GPs for monitoring and providing medication.
Summary
I have used fever to remind us of the standard medical model. I have shown where a medical model approach to ADHD does not fit the problem, and certainly does not fit with our usual CAMHS standards. The result is that child psychiatry is a business that is so successful in attracting customers that we face going bust.
Psychiatry has still not learnt from earlier empire-building bouts of hyperactive business. For example, we fashioned and handed out a disease label for conduct disorder (Child 2000) yet some services summarily return such referrals to the sender, unseen and with the very labels on them that mark our claim over them! Will we learn this time? Probably not, because we believe we have too much to lose if we stop overstretching the medical emperor's new clothes to cover what they should not. I am not saying we do not have clothes, just that the ceremonial robes will not do for hill-walking.
I have outlined a 'hill-walking' way of managing things. Figures 2 and 3 represent the argument in summary, showing ways to conceptualise ADHD services that 'fly' or 'crash'. On the basis of good general working relationships with other agencies in the team of agencies for your district, and with a good understanding of what 'ADHD' is about, with appropriate referrals that do not sit on a waiting list or get seen at a prejudging ADHD clinic, a CAMHS will have no avalanche.
References
Child, N. (1991). Quality thinking and a formula they can't refuse. Psychiatric Bulletin of the Royal College of Psychiatrists, 15, 476-477 [Click here to download pdf]
Child, N. (1996). How true storytelling lost its place. Context, 28 (Autumn), 34-37
Child, N (2000). The limits of the medical model in child psychiatry. Clinical Child Psychology and Psychiatry, 5, 11-21
Child, N. (2001) Systemic practice: fitting and teaming up. Thinking Families (with Context), 57 (October), 1-2
Child, N. (2002). Lanarkshire Guidelines for ADHD. Available on request or from www.forallthat.com
Gustafsson, P., Holland, L., Child, N., Nunn, K., Nicholls, D. & Lask, B. (2001). Uluru revisited. Clinical Child Psychology and Psychiatry, 6, 593-598
Hill, P. & Cameron, M. (1999) Recognising hyperactivity: A guide for the cautious clinician. Child Psychology and Psychiatry Review, 4, 50-60
Scottish Executive. (2001). For Scotland's children: Better integrated children's services. Edinburgh: The Stationery Office Bookshop
Scottish Intercollegiate Guidelines Network (2001) SIGN guidelines on attention deficit and hyperkinetic disorders in children and young people. Edinburgh: SIGN Secretariat
Smith, R. (2002). In search of 'non-disease'. British Medical Journal, 324, 883-885
Szatmari, P., Offord, D., & Boyle, M. (1989). Ontario child health study: prevalence of attention deficit disorder with hyperactivity. Journal of Child Psychology and Psychiatry, 30, 219-230
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