Podcast Transcript
ADHD and Intellectual Disability
Summary:
This podcast provides an in-depth discussion on the relationship between intellectual disability (ID) and attention-deficit/hyperactivity disorder (ADHD) in children and adults. The key points are:
- Intellectual disability is characterized by impairment in adaptive behavior and an IQ score of seventy or below. Levels range from mild to profound.
- ADHD and ID frequently co-occur, with around fifty percent of individuals with ID also meeting criteria for ADHD.
- The symptoms of ADHD in individuals with ID may differ from the general population, requiring consideration of mental age when assessing for ADHD.
- Treating the ADHD symptoms in individuals with ID can improve their ability to learn and function, even though there is no direct treatment for ID itself.
- Parents and educators should have realistic expectations and provide structure and consistency to support individuals with both ID and ADHD.
- While the dual diagnosis presents additional challenges, there are effective treatments available, and a reasonable prognosis can be achieved with appropriate interventions.
Max Wiznitzer, MD
Max Wiznitzer, MD, is a pediatric neurologist at Rainbow Babies & Children’s Hospital in Cleveland, Ohio. He is a professor of pediatrics and neurology at Case Western Reserve University. He has a longstanding interest in neurodevelopmental disabilities, especially ADHD and autism, and has been involved in local, state, and national committees and initiatives, including autism treatment research, Ohio autism service guidelines, autism screening, and early identification of developmental disabilities. He is on the editorial board of Lancet Neurology and Journal of Child Neurology and lectures nationally and internationally about various neurodevelopmental disabilities.
Eugene Arnold, MD, MEd
Eugene Arnold, MD, MEd, is professor emeritus of psychiatry at The Ohio State University, where he formerly was the director of the division of child and adolescent psychiatry and vice-chair of psychiatry. He is a co-investigator in the OSU Research Unit on Pediatric Psychopharmacology. He has forty-five years of experience in child psychiatric research, including the multi-site NIMH Multimodal Treatment Study of Children with ADHD (MTA), for which he was executive secretary and chair of the steering committee. For his work on the MTA, he received the NIH Director’s Award. A particular interest is alternative and complementary treatments for ADHD. His publications include ten books, more than seventy chapters, and more than four hundred articles.
Learning Objectives
- Explain the difference between ADHD and intellectual disability.
- Describe the common causes of intellectual disability.
- Identify professionals who can diagnose and treat intellectual disability and ADHD.
- Explain how parents can support their child with ADHD and intellectual disability.
- Explain the importance of interprofessional collaboration in the diagnosis and treatment of ADHD and intellectual disability.
The following transcript has been edited for clarity.
Announcer (00:00): You are listening to Pocket MD training on ADHD in children and adults.
Dr. Max Wiznitzer (00:07): Welcome to another podcast of Pocket MD. My name is Max Wiznitzer. I am a professor of pediatrics and neurology at Case Western Reserve University and co-chairman of the professional advisory board for CHADD. Today's topic is ADHD and intellectual disability, and we have the pleasure of having our guest expert being Gene Arnold. He's professor emeritus at OSU, who will also fill you in on the rest of his credentials. Gene, welcome.
Dr. Eugene Arnold (00:41): Thank you. Yes, I've been doing research on ADHD treatments and autism for about fifty years. I'm CHADD's Resident Expert. I have a grandson with autism, a grandson with ADHD, and another grandson with intellectual disability. I have a vested interest in this topic.
Dr. Max Wiznitzer (01:08): Let's see what we can do to help illuminate the knowledge of our listeners today. You can also do this both from the research as well as from the practical experience that you've had. Let's start with something simple. How do we define intellectual disability?
Dr. Eugene Arnold (01:23): Intellectual disability has been known by various names, beginning with intellectual deficiency with three categories, moron, imbecile, and idiot. Then the name was refined to mental retardation, because those designations had bad connotations. And then, eventually, mental retardation fell out of favor, and the term intellectual disability was substituted in the most recent DSM Diagnostic and Statistical Manual. To meet the diagnostic criteria for intellectual disability, there have to be at least two important thresholds. The most important is an impairment of adaptive behavior, adaptive function. The other is a standardized intelligence test at least two standard deviations below the normal mean for the population, which would be an IQ of seventy or below. If the IQ, the intelligence quotient, is seventy to fifty-five, that's mild ID. If it's fifty-five to forty, that's moderate, and then of course below that is severe and then profound, going down by one standard deviation each.
The standard deviation on IQ tests is fifteen. It's easy enough to count down. When you go between seventy and eighty-five is sometimes called borderline, but it's actually low average. If you would look at a distribution graph of IQ, you would see that most of the population falls within eighty-five to one hundred and fifteen, which would be one standard deviation, and then another significant proportion comes in at the next standard deviation, which would be either at the top end one fifteen to one thirty or at the bottom end would be eighty-five to seventy. It's appropriate that we are talking about this topic, because the original discovery that amphetamine helped ADHD was made by Bradley in the 1930s on a population of children who had what was at that time called mental retardation [and] now would be called intellectual disability. And then, of course, in more recent times, you were not allowed to diagnose ADHD in the presence of pervasive developmental disorder, which included autism and a few other related categories because it was considered that the hyperactivity and inattentiveness were part of the autism syndrome. However, starting with DSM-IV , I believe, we now are allowed to diagnose both in the same person, and there is great genetic overlap in addition to the clinical overlap.
Dr. Max Wiznitzer (04:43): May I just throw in something very quickly there? I would say it's not that we're allowed, it was recognized that ADHD did occur in that population because those of us who didn't believe the criteria never accepted the fact that ADHD couldn't occur, because many of those children got better when you put them on ADHD treatment.
Dr. Eugene Arnold (05:02): We were doing it before and treating both disorders before, but now it's official sanction.
Dr. Max Wiznitzer (05:08): Let me ask a simple question. What are some of the common causes of intellectual disability?
Dr. Eugene Arnold (05:14): Of course, I mentioned the adaptive functioning. In the more severe cases, there's a delay of self-care abilities, toilet habits, eating, sanitary practices, even things like toothbrushing may be problematic. In the milder cases, those milestones, those developmental milestones are generally achieved, but at a lower rate, slower, later in life and slower than would be considered normal.
Dr. Max Wiznitzer (05:47): Besides, I think everyone understands that there are genetic reasons why intellectual disability is present. Are there other causes if you want to fill it together that way, besides things like genetics and trauma, that might lead to an ID that might cause an individual to have ID?
Dr. Eugene Arnold (06:04): One of the big problems is birth trauma, brain insult at the time of birth. Of course, that would include things like premature birth, or intrauterine infections could do it, and all these things can also be causes of ADHD or at least put a person at risk for ADHD; again, the clinical overlap here. Other things can be traumatic brain injury early in life. Sometimes poor environments can contribute to it. This will be variable of course with the genetic endowment.
Dr. Max Wiznitzer (06:40): If I may offer some in utero, a toxic exposure is alcohol, excessive alcohol, that we know that, and in the old days, not as much nowadays, but in the old days when there were extremely high lead levels in the children, we would see obvious intellectual disability as a consequence of that rather than just a drop of a few IQ points and some speech delay in addition to the ADHD that can occur. Like you pointed out, almost anything that can insult the brain can lead to intellectual disability and can lead to ADHD in that situation. Two questions. One is how often do they co-occur? That's question number one.
Dr. Eugene Arnold (07:17): If you start with ADHD and check for intellectual disability, there's not much difference from the population percent of ID. That's pretty much the same. In ADHD, there are about four or five points difference on the mean IQ between those with ADHD and the population mean. If you start from that viewpoint, ADHD can occur in a person of any intellectual endowment including geniuses. But if you start from the other viewpoint from that of ID, which is less prevalent, intellectual disability being less prevalent than ADHD, a very high proportion of those with ID would have ADHD, at least ADHD symptoms, probably half. For example, with children with autism, about half also meet criteria for ADHD diagnosis. For those with intellectual disability without autism it probably would be a little lower percent, but still much higher than the regular population and partly attributable to the fact that the risk factors that we talked about apply to both disorders. So, if you have the same risk factor, you're more likely to have both disorders.
Dr. Max Wiznitzer (08:45): And we also have to remember that, since ADHD is highly familial, that a child with intellectual disability who's born into a family where others have ADHD may have the ADHD just as a consequence of the family tendency rather than of the ID.
Dr. Eugene Arnold (09:01): Yeah, and you also have the fact that parents with ADHD may not be able to provide the optimal environment to promote normal intellectual development of the children. You have this vicious cycle going.
Dr. Max Wiznitzer (09:17): Let's look at individuals who have both diagnoses. Do they share common symptoms, or how do you differentiate between a child with ADHD and a child with intellectual disability?
Dr. Eugene Arnold (09:28): ADHD has very specific signs and symptoms listed in DSM, things like inattention, distractibility, inability to finish things that they start, difficulty organizing, losing things, being disorganized, and inept. Now, the ineptness also may occur with ID without ADHD, but they tend to be overactive, less distractible, and it's mainly a problem of adaptation, behavioral adaptation, whereas a child with ADHD may go through most developmental milestones at the regular time. They toilet train okay, and they learn to dress themselves, and they can catch the school bus by themselves and things like that, their adaptive behavior is not so bad. It's more so in the area of executive function where you have to plan out a project and carry it through to completion, which would apply to school projects, of course. The person with ID, the child with ID without ADHD also will have trouble at school, but it's because they can't understand or they can't just do the thing and not so much that they're distracted and unable to carry out a project in an organized way.
Dr. Max Wiznitzer (10:52): When we look at individuals with intellectual disability who also have ADHD, is their level of disability reflected by the symptoms and signs of the ADHD? In other words, we know that individuals without intellectual disability, for instance, as they get to the adult years, we'll have less hyperactive features. They'll have more inattentive features, they'll have more problems with executive functions in comparison to the four- and five-year-olds who are symptomatic. Do we see the same pattern depending on the intellectual level of the children with intellectual disability? That is, if I'm a twelve-year-old who has the IQ of a four- or five-year-old, will I show the ADHD symptoms of a four- or five-year-old? Will I show the ADHD symptoms of a twelve-year-old? In other words, are the ADHD symptoms more linked to mental age or chronological age?
Dr. Eugene Arnold (11:43): The DSM says that the symptoms have to be abnormal for the age of the child. In assessing those, you have to take age into consideration. Now, the question that I think is unsettled is whether, in an evaluated child or adult for that matter with intellectual disability, do you take their mental age into consideration in deciding whether the symptom is abnormal for that? I think it's done both ways, and part of it is whether you have an excuse to treat the symptom. I think the diagnostic assessment is fudged sometimes to justify treatment when the clinician thinks that treatment is indicated, but the actual objective data don't quite justify it. Of course, there's a diagnosis that can be used called NOS, not otherwise specified, that could be used in that situation.
Dr. Max Wiznitzer (12:42): If there's an individual with intellectual disability in whom we suspect ADHD, who usually does the assessment in order to confirm or refute that impression?
Dr. Eugene Arnold (12:52): For the assessment for intellectual disability, you need someone who can do a standardized intelligence test; that would ordinarily be a psychologist, a clinical or school psychologist. They could also diagnose the ADHD. But in practice, in many cases, the ADHD diagnosis is done by a pediatrician or child psychiatrist or child neurologist.
Dr. Max Wiznitzer (13:20): Or developmental pediatrician or we'll call it a specialist. Are there some specific things that you have to look for in the ID population that you wouldn't look for in the normal-intelligence population when you do these assessments and others? What are the challenges in order to make sure you make the diagnosis correctly?
Dr. Eugene Arnold (13:37): Yeah, as I mentioned, daily living skills would probably be one of the big things that would be necessary. Adaptive behavior impairment would be necessary for ID, and it's not necessary for ADHD.
Dr. Max Wiznitzer (13:51): But if I have a person with ID known with ID, but I want to assess them for ADHD, is there anything special I'm looking for?
Dr. Eugene Arnold (13:59): You have to make the adjustment for the fact that they're not operating at their chronological age level. I don't know of any hard-and-fast rule to apply to it.
Dr. Max Wiznitzer (14:11): I think that's basically the key criterion that we have to make sure that we look at them at where they are and not where we expect them to be, and then judge accordingly. Now, for treatment and for interventions, what kinds of interventions are recommended for individuals who have both intellectual disability and ADHD?
Dr. Eugene Arnold (14:28): The interventions for the two disorders are somewhat different. The most effective proven treatment for ADHD is stimulant medication, and also some other medication have good evidence. However, there's no pill for ID. People may wish for it, but we currently don't have any medical treatment for ID. There are other treatments though: educational, occupational therapy, and so forth can train or educate children. There's someone who even wrote a book that claims that IQ can be taught by going through the sort of exercises that IQ tests use, the teaching to the test. Most people with ID and most of those with ID have mild ID. The frequency goes down as you get more severe, but those with mild ID can be educated and learn eventually; it takes them longer. They have to work harder at it, but they can learn things. As I said, I don't know of any pill that helps that. Now if they happen to have ADHD along with their ID, then treating the ADHD will make it easier for them to learn what they need to from the ID side.
Dr. Max Wiznitzer (15:53): Is there anything different about the treatment of an individual with ID who has comorbid ADHD when you're treating the ADHD? Are there data telling us how successful we are with medication treatment or with using other strategies that would be used for other individuals with ADHD?
Dr. Eugene Arnold (16:11): That's a good point regarding what you can expect for example, stimulant medication. There are several studies showing that it's somewhat less effective in preschoolers than it is in school-aged children in the normal population, and there's a hint in the literature that those with ID don't respond as well even at the same mental age --don't respond as well as those who don't have ID, and this is probably because of differences in brain function and structure.
Dr. Max Wiznitzer (16:49): If a child came to you who has ID and comorbid ADHD, what advice would you give to the parent in terms of, we'll say, the multimodal management of the ADHD in those children?
Dr. Eugene Arnold (17:02): First of all, you need to explain what each disorder is and what the implications are for it and set expectations that are appropriate. For the ADHD, it would be that it takes longer for this youngster to learn the normal things. Some people, you can throw them in the water when they're three years old and they start paddling away, they just naturally learn to swim. Others have to take swimming lessons, and this is a child who has to take lessons to learn to do what other people do naturally. Sitting still in class, paying attention, organizing things, learning habits. Habits are the friend of a person with ADHD, because once you have a habit, then you don't have to pay attention to it anymore, so the attention deficit is not such a big problem. For the child with ID, the expectation has to be set realistic with their abilities, and that is, depending on how severe it is, they may never be self-sufficient in the sense of earning their own living. The parents need to make preparations for that. They may always need some support, some supervision.
Many of them can be taught eventually if they live alone and get used to that environment and learn where the bus is and so forth, can function reasonably well and perform essential services—things like garbage collection, stocking shelves, other rote things, sweeping floors, cleaning, washing dishes, and so forth. Somebody has to do that and it's boring for a person of normal intelligence, so they can learn to do that, but parents shouldn't be saving for college for this particular child. And whereas with ADHD, many people with ADHD do successfully go through college and become very good professionals or other people with highly skilled jobs.
Dr. Max Wiznitzer (19:07): If you're looking at individuals with intellectual disability and with ADHD, how often is it that somehow the ADHD is overlooked or not treated in comparison to the general population?
Dr. Eugene Arnold (19:21): Now, I don't really have an answer for that question, but I suspect that in many cases I think it's likely to be discovered because if they have ID, they're going to get into special education and other services where I think the ADHD would be noticed and referred for evaluation of possible diagnosis. So actually they may have their ADHD diagnosed at a higher rate than the normal population. That's an interesting research question.
Dr. Max Wiznitzer (19:52): I have had patients where they clearly had ADHD features, but they were overlooked by other clinicians or the clinicians felt that they couldn't possibly have it because of their level of intellectual functioning and therefore did nothing about it, but when you treated it with the standard treatments we do for ADHD, there was definitely an improvement. As you pointed out, improvement in life functioning both for the individual with the ADHD as well as for their family unit.
Dr. Eugene Arnold (20:20): And of course it's important to think about ADHD because there's comparatively easy and reasonable treatment for that, whereas the ID treatment is much more laborious and long-term and expensive.
Dr. Max Wiznitzer (20:38): What can parents and educational personnel do to support a student who has both ID and co-occurring ADHD in order to make sure that their life experience is basically reaching, as best as they can, the potential they have?
Dr. Eugene Arnold (20:56): One of the things, of course, as I mentioned before, is setting the correct expectations. Some of the things, those associated with ADHD, can improve with treatment. Those associated with ID need to have different kind of expectation, a lower expectation in general, but it would be unfair to the child to set too high an expectation. On the other hand, setting too low an expectation could result in a self-fulfilling prophecy.
Dr. Max Wiznitzer (21:29): How well do they do with structure, routine, and consistency?
Dr. Eugene Arnold (21:32): Structure would be important in both disorders. Of course, the disorganized child with ADHD may benefit a little more from it in terms of shoring up their function that they start performing better. Those with ID also benefit from it more in the sense of psychological support that they know what to expect all the time.
Dr. Max Wiznitzer (21:57): From what we've been saying today, it appears that ADHD does occur in individuals with intellectual disability, that sometimes it may be missed, but it's important to identify it because of the ramifications in terms of their functioning, and that there are effective treatments that are available once that identification occurs. Is there anything else that you would like to add before we end?
Dr. Eugene Arnold (22:22): Just that the dual diagnosis of ADHD and ID should not discourage from treatment. It's not a hopeless situation. Each disorder has its own treatments and those can be applied. It means that the caregivers, the parents, or other people who are taking care of the youngster, have more to do. They have to work a little harder in order to arrange treatment for both disorders, but there can be a reasonable prognosis in the case of both, either separately or together.
Dr. Max Wiznitzer (22:58): I thank you, Dr. Arnold, for all your knowledge and wisdom that you imparted to our listeners today, and for anyone else who wants to know, there are references that are available that can be obtained on this topic. I am Max Wiznitzer, the moderator for today's session on ADHD and those with intellectual disability, and I thank everybody.
Announcer (23:22): Pocket MD is brought to you by CHADD with funding from the US Centers for Disease Control and Prevention, and in partnership with the Rainbow Center at Rainbow Babies and Children's Hospital.