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Monday, March 31st, 2014
The latest prevalence estimate of Autism Spectrum Disorder (ASD) – 1 in 68 – reignites conversation that we may be overdiagnosing ASD. In part, to some the estimate just feels too high based on clinical and personal experience. And there is worry that we may be flooding an already overwhelmed evaluation and treatment system.
These concerns echo the debates that surrounded the changes in diagnostic criteria that were introduced in the DSM-5 in May 2013 which, to some, were implemented to protect against overdiagnosis of ASD, as I described last December:
The reformulation of the diagnostic criteria – which led to a discontinuation of the category of Asperger Syndrome in favor of a broad-based category of Autism Spectrum Disorder (ASD) – spurred concerns that many youth would no longer qualify for a diagnosis and hence have their intervention options limited. Others suggested that more precise diagnostic criteria are needed to ensure that ASD does not get overdiagnosed. While we await empirical resolution via publication of well-designed studies, it’s clear that the DSM-5 debate will stand out as an important time in which we wrestled (again) with the best way to be inclusive in diagnosis without expanding diagnostic criteria too broadly.
As a result of the changes in DSM-5, it may be that a few years from now we will see a “recalibration” of the prevalence of ASD. The speculations have been that about 10% of children now diagnosed with ASD will no longer meet criteria.
What do we make of these changing estimates in the prevalence of ASD, which have increased tremendously over the past decade and may, sometime in the near future, begin to decrease? This complex issue does not lend itself to a singular answer. Considering a number of points may help to provide some perspective on how we discuss this question.
PREVALENCE RATES FOR DISORDERS CAN BE “HIGH”
While, as noted above, clinicians, researchers, and policy makers often attempt to interpret the rate of a disorder as a means of ensuring appropriate diagnostics without overdiagnosing, the fact is that there is no magic number or prevalence rate for a disorder. Consider the following:
- Epilepsy is estimated to affect somewhere between 4-10 per 1000 people; and nearly 10% of the population will experience a seizure in their lifetime
- Asthma affects almost 10% of children
- More than 8% of the population is reported to have diabetes
The point? Disorders which can be validated biologically can affect large numbers of people in the population. This means that they are common disorders – not overdiagnosed conditions. The implication for ASD? Simply put, an estimated prevalence of “1 in 68″, in and of itself, does not necessarily imply overdiagnosis.
RATES CAN CHANGE OVER TIME
Part of the concern with the rate of ASD is that it has changed so much over the past decade. The estimates made by the Centers for Disease Control and Prevention (CDC) have gone from 1 in 150, to 1 in 110, to 1 in 88, and now to 1 in 68. The rates of asthma have also gone up over the past decade, though not nearly as dramatically as those for ASD. A combination of factors have influenced this increased prevalence of asthma, including better recognition and diagnosis, changes in the definition of the disorder, and possibly increases in pathogens in the environment. The takeaway here is that an increase in prevalence over time is not a sufficient argument for overdiagnosis.
THE KEY CONCERN IS THE ROOT OF THE INCREASE OVER TIME
The crux of the debate about ASD is that we may be artificially increasing the prevalence. To consider this point, we need to focus on two two related factors that are primarily responsible for the dramatic changes in ASD prevalence.
First, there is much better screening, recognition, and evaluation. This is a positive step forward – early evaluation leads to early intervention. But as noted in the most recent CDC report, there are still children (primarily those in specific ethnic groups) who are not diagnosed at the same “high” rate as others. So simply lowering the bar for early evaluation is not necessarily a good step forward, and in fact may be counterproductive for many children in the population.
Second, there has been an increase in diagnosing “higher functioning” ASD, that is, ASD without a compromised cognitive level. This is where the conversation about overdiagnosis starts – and where the DSM-5 may lead to a reduction in prevalence over time. The sticky point is that as ASD, by definition, is recognized to occur along a spectrum of severity, it becomes hard to know where to draw the line. At what point would we be missing cases that could profit from intervention? At what point are we pathologizing normative variation in social functioning? There is where we need more informative data on the impact of interventions for those diagnosed and more pointed discussion.
Let’s look at a very different example – potential changes in how high blood pressure is being diagnosed in those 60 years of age and older. New guidelines have suggested that the target blood pressure for determining treatment is 150/90, as opposed to 140/90. The result would be that millions of adults over 60 would no longer be “required” to take medication for high blood pressure. This is a current controversy in medicine and it is being debated. The point here is that the biomedical and health sciences have to make these kinds of decisions for many disorders, and that controversies continue to arise. In other words, these are not simple issues, and they are not resolved easily. We continue to gather more information and bring more opinions to the table to come up with our best practices – and this same principle applies to the current and future conversations about ASD.
SO IS ASD BEING OVERDIAGNOSED?
Right now, this is an important question to ask, but rather than demand an answer, we need to gather more informative data and have more informed discussions that go beyond the prevalence rate. We have these discussions frequently about attention-deficit hyperactivity disorder (ADHD), and they continue. We worry that too many kids are being arbitrarily diagnosed with ADHD and that we may artificially inflate rates of ADHD by making inappropriate demands of toddlers and young children. The concern with ADHD is that we may be preventing kids from being kids, slapping them with inappropriate labels, and giving them medications that are not needed.
The concern with ASD is somewhat different. We are not over-medicating youngsters who are receiving a diagnosis of ASD, particularly those who are “high functioning.” We are offering behavioral interventions to improve social and cognitive skills. What we need to know is if some kids who would receive these kinds of interventions don’t need them or don’t profit from them. That’s essentially the tipping point in the argument described above about how to define high blood pressure. We should move beyond the prevalence rate and begin to look more closely at the efficacy of interventions and if there are better ways to define which kids can be best served by a diagnosis.
But what we don’t want to do is arbitrarily decide that the prevalence rate is “too high” and that we need to lower the bar for screening and evaluation. That would be a big mistake and undermine all the progress made to date in early surveillance and early intervention. Whatever the “true” prevalence rate is (and it will be a moving target), what we do know is that many young children can profit from early intervention and that we need to keep momentum going on understanding more about the causes of ASD, how to best diagnosis it, and how to develop even more powerful interventions.
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Friday, March 28th, 2014
It is now estimated that 1 in 68 children are diagnosed with Autism Spectrum Disorder (ASD), based on a report issued by the Centers for Disease Control and Prevention. This detailed CDC report deserves a close look as there are a number of important findings on the prevalence of ASD and factors that influence evaluation and diagnosis.
THE RATE KEEPS INCREASING: As described by the CDC, the new estimate is 30% higher than the prior estimate made just 2 years ago (1 in 88). The estimated prevalence of ASD has gone up tremendously in the last decade, and it is assumed that improved recognition and diagnosis is the primary factor. The implication here is that we have underestimated the true rate of ASD and as such the new data suggest an urgency in mobilizing resources to understand the causes and accelerate the delivery of interventions (see, for example, the reaction from Autism Speaks to the new estimate).
SEX OF CHILD MATTERS: ASD has always been more prevalent in boys. The new data continue to support that, as 1 in 42 boys in the study received a diagnosis, as compared to 1 in 189 girls. The reasons for this sex difference are still not well understood. But it’s clear that boys in particular are especially likely to be diagnosed with ASD – 1 in 42 is a very high prevalence for any disorder. So anticipate increased efforts at screening for ASD by pediatricians, especially for boys. And it is noted that ASD should be screened for in girls with more intensity as well, as 1 in 189 is a high prevalence for a disorder.
ETHNICITY MATTERS: While the rates of ASD continue to go up, it is diagnosed more frequently in white, non-Hispanic children. Non-Hispanic white children are 30 times more likely to receive a diagnosis as compared to non-Hispanic black children, and nearly 50% more likely to be diagnosed than Hispanic children. Evaluative and diagnostic efforts need to increase for children in these ethnic groups.
ALL LEVELS OF COGNITIVE FUNCTIONING ARE AFFECTED: Nearly half (46%) of the diagnosed cases in the study had cognitive abilities in the average or above average range. This is potentially one factor that has increased the estimated prevalence over time, as there is more recognition of symptoms of ASD without cognitive/intellectual impairment. Level of cognitive functioning is important clinically in terms of managing other potential conditions and planning interventions – but it’s clear that ASD is being diagnosed across all levels of functioning.
ASD IS STILL DIAGNOSED LATER THAN IT COULD BE: Although recognition of ASD has certainly increased over the last decade, the evaluative and diagnostic efforts are still being done later rather than sooner. The CDC suggests that less than 50% of the diagnosed cases were evaluated before age 3, and that the majority of diagnoses were made after age 4. Reliable screenings of ASD can be made by 2 years of age, and it is imperative that early detection is encouraged, as there are interventions that can begin at these earlier ages. So while detection of ASD has improved over time, we need to see evaluations done at younger ages to ensure that children with ASD receive interventions as early as possible.
WILL THE RATES CONTINUE TO RISE?: This question is raised because of the change in diagnostic criteria offered by the DSM-5, which was introduced in May 2013. Note that the current study collected data in 2010, using the prior version of the DSM (the DSM IV-R). There has been much speculation that the prevalence of ASD will decline given the new criteria. However, we are years away from getting the answer to that question, given the amount of time that it takes to mobilize these intensive data collection efforts. But it’s something to keep in mind for the future.
WHAT ARE THE MOST IMPORTANT IMPLICATIONS OF THE “1 in 68″ STUDY?: Clearly, the need for earlier detection is key – we can’t confuse the increasing recognition with early detection. More vigilant efforts need to be applied to evaluate children in every ethnic group. And while the rate of ASD in girls is much less than that for boys, keep in mind that “1 in 189″ is still a very high prevalence, so efforts to detect ASD in girls should also be intensified. For parents, the most important point is to be aware of early signs of ASD, and to work collaboratively with your pediatrician to monitor your child’s early development and seek out further evaluation if necessary as young as possible.
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Wednesday, December 18th, 2013
Two themes stand out when I reflect on autism research in 2013.
First, there was substantial debate about how we diagnose autism, primarily spurred by changes introduced in DSM-5 (which was published in May). The reformulation of the diagnostic criteria – which led to a discontinuation of the category of Asperger Syndrome in favor of a broad-based category of Autism Spectrum Disorder (ASD) – spurred concerns that many youth would no longer qualify for a diagnosis and hence have their intervention options limited. Others suggested that more precise diagnostic criteria are needed to ensure that ASD does not get overdiagnosed. While we await empirical resolution via publication of well-designed studies, it’s clear that the DSM-5 debate will stand out as an important time in which we wrestled (again) with the best way to be inclusive in diagnosis without expanding diagnostic criteria too broadly.
Second, we are seeing more research on the early diagnosis of ASD, or at least detection of early warning signs, using methods like tracking eye movements of babies when looking at a human face. While this line of work will need to continue to refine the validity and feasibility of the approach – particularly when studying infants – it is an intriguing approach that may eventually have important implications for delivering interventions in the first year of life. Given the proven utility of early intervention, the hope is that the earliest interventions may hold the most promise for promoting development.
Wherever these research directions take us, we know for sure that early detection and intervention is essential. That’s one message that has not changed in 2013.
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Thursday, November 7th, 2013
Early diagnosis of autism spectrum disorders (ASD) offers the promise of early intervention – with the premise being the earlier, the better. New research suggests that we may be on the horizon of finding signs of ASD in the first 6 months of life. Here’s the breakdown of why this study – which examined attention to eyes in infants as a predictor of a diagnosis of ASD in toddlerhood – is so important.
Why Is This Study Design Powerful? This study – which builds on substantial prior research on eye contact in ASD – uses a powerful longitudinal design to search for the early signs of ASD in infants, including some at high risk (babies of older siblings with ASD). These design features give confidence in the results – the sampling frame goes from early infancy through the typical age of first diagnosis of ASD, and the high-risk component ensures enough cases to draw meaningful conclusions. And the construct of interest – attention to eyes – has been well-studied, is theoretically grounded, and can be measured with precision.
Why Are The Findings Provocative? Two reasons. First, while ASD (or the risk, or liability, to develop ASD) is assumed to be present at birth, early signs of ASD have been elusive. This study offers hope that by detecting a lack of attention to eyes in the first 6 months of life may offer one potentially powerful screen for risk for ASD. But there’s more. An especially novel finding is that infants later diagnosed with ASD started out in life attending to eyes – but that that ability declined over time. This may eventually be a clue in terms of underlying brain mechanisms – and it also suggests that if these fundamental mechanisms are “in tact” at birth and then decline, perhaps there is even more room for change with very early intervention. Either way, a strong signal of risk in the first 6 months of life may be translated – perhaps rapidly – into very early intervention strategies.
What’s The Take-Home Message? Parents have been encouraged to be mindful of some of the signals of risk for ASD in the early years – including 7 early signs of ASD. Although this study has not yet led to formal recommendations for parents, it does suggest how important face-to-face interaction is during infancy – and also highlights that parents should be vigilant about seeing how their baby reacts when eye contact is expected. The way a baby looks at the human face changes a lot over the first year in life – but the constant is that they spend a lot of time looking at it. The suggesting from this new research is that babies at risk for ASD show a decrease in their interest in the face during infancy. If this is happening, it is certainly worth bringing to the attention of a pediatrician, who will be positioned to look for other developmental milestones and indicators.
What’s The Future? Research studies are especially influential if they give a glimpse into the future. Here the hope is that a screening protocol can be developed to route infants into very early intervention – a developmental time that may hold promise for a lot of plasticity and response to intervention. Bear in mind that some of the most exciting findings to date about intervention – based on application of the Early Start Denver Model (ESDM) – demonstrated that one of the results of intensive intervention is changing the brain response to the human face, with normative patterns of brain activity achieved in some cases. Starting that process in infancy might lead to even more effective intervention programs for ASD.
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Tuesday, July 30th, 2013
Researchers are developing methods to analyze movement patterns in children with autism spectrum disorder (ASD), with the hope that these may be invaluable tools for aiding the diagnostic process and eventually designing interventions. While movement difficulties have long been recognized to be part of ASD, these newer approaches are embracing the idea that movement is a core process via which infants develop their way of interacting with the world – one that it is critically linked with the development of a number of brain areas that underlie social and cognitive development.
Consider the ways in which babies use movement to learn about the world. Think about how a baby pulls themselves up, starts to crawl, and learns to walk – from the perspective of how these movement-based actions allow them to explore their world. Think about how they use their hands to experience and manipulate their physical and social environment. These processes have been appreciated by developmentalists for a very long time. But what’s new is understanding how important movement is for establishing brain development. Recent advances in neuroimaging are showing, for example, how the cerebellum is not just specialized for movement – it also has subsections involved in processing cognitive and emotional stimuli. Movement isn’t just about movement – it’s a fundamental vessel for integrating information out in the world and then translating that information into action.
We will continue to see more and more evidence for movement-brain-cognition links in the future. But the bottom line is that encouraging movement as a way of exploring the physical and social world in infancy and toddlerhood is a very good thing for the brain. And it may turn out that it will also be one avenue to help improve both diagnostics and generate potential interventions early in life for children with ASD.
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