In the last few posts I laid out a 3D picture of ASD that integrates degree of atypicality, level of general intelligence, and age (or Time). In this model, we can think of atypicality as a chunk of ice floating in the water. The size of the chunk of ice corresponds to the degree of atypicality, and the water temperature corresponds to the IQ. Just as in the real world, the warmer the water (i.e. the higher the IQ) the faster the “ice” (atypicality) melts over time.
Children who start out with moderate to mild atypicality combined with normal IQ, shed many of the outwardly visible features of ASD during childhood: Eye contact and language improve, while social isolation, stereotypies and sensory issues diminish. As adults, some of these individuals no longer meet the behavioral criteria for ASD.
Even though the outwardly defining features of ASD (stereotypies, echolalia, etc.) have faded, however, these individuals continue to manifest the cognitive profile of persons on the spectrum: relative weakness in skills tapping “theory of mind” and “central coherence,” which translate into persistent difficulty understanding social signals or seeing the “big picture.”
These individuals also are at risk for neuropsychiatric disorders (anxiety, depression, mood disorders, OCD), all of which tend to run in families of individuals with ASD. Thus, even though a child may gradually “outgrow” his or her ASD diagnosis, the child may simultaneously “grow into” an anxiety disorder, depression, or a mood disorder. As you might expect, there are lots of individuals who manifest persistent features of ASD, plus neuropsychiatric impairment. It’s not a matter of “either/or,” but “both/and.”
In the first part of this thread we discussed the symptoms of ASD, and the “natural history” of improvement over time – first noted by Leo Kanner in 1943. In the second part of this thread, we introduced the idea that IQ is independent from atypicality. Every individual with ASD has a unique combination of degree of atypicality, and level of intelligence. We can depict this relationship using an XY graph, with severity of atypicality on the horizontal (X) axis, and IQ on the vertical (Y) axis.
IQ is the single biggest factor influencing long-term outcome in children with ASD. This has been known since the 1970’s. Think of atypicality like a hunk of ice, floating in the water. The severity of the atypicality is equivalent to the size of the hunk of ice: it can be a huge iceberg, or a tiny little piece. Think about IQ as being equivalent to the water temperature: freezing cold = low IQ; warm, tropical water = high IQ. Now ask yourself: If we start with two identical hunks of ice, and drop one into the Arctic Ocean and the other into the Caribbean, which will melt faster? The answer is obvious.
A lot has happened since I posted Part I of this thread. I grieve for all of the families in Newtown who lost loved ones. I will have more to say about those events shortly, but in order for my comments to make sense, we need to finish laying the groundwork.
In Part I of this thread, I described the X axis of a graph, on which I displayed the symptoms in the four areas impacted by ASD: Social, Language, Repetitive Behavior, and Sensorimotor. The child’s development in these four areas is off the track (“atypical”). Notice that there’s nothing on the X axis about IQ. That’s because atypicality is separate from IQ. Because IQ is independent of atypicality, we put IQ on its own axis:
Figure. IQ scale.
IQ tests are designed so that the average (“mean”) score = 100. The “spread” in scores above or below the mean is described in “standard deviations” (SD). On most IQ tests, 1 SD = 15 points. Intellectual Disability is defined in part by having an IQ score that is 2 or more SD below the mean (i.e., less than 70). This is roughly the same as the 2nd to 3rd percentile. At the other end of the scale, persons with IQ’s of 130 or higher are performing at or above 97th to 98th percentile, relative to the population as a whole. (Based on “Making Sense of Autistic Spectrum Disorders,” figure 5.2)
An individual can have any combination of intelligence and atypicality, just as someone can have any combination of height and weight. Another way to think about the relationship between IQ and atypicality is to imagine that you are waiting for a train: The train may be late, on time, or ahead of schedule; this corresponds to the overall rate of intellectual development (IQ). Additionally, the train may have one or more wheels off the track; this corresponds to atypicality. Each is important, but they are separate issues. In order to depict this relationship visually, we combine the X axis (atypicality) and the Y axis (IQ). Now we have an XY graph, on which we can map each child’s unique combination of atypicality and IQ.
Figure. XY graph, depicting the relationship between degree of atypicality on the X axis, and level of intelligence on the Y axis.
We have also displayed the regions that roughly correspond to the terms autism, PDD-NOS, and Asperger Syndrome. Persons with severe-moderate atypicality combined with an IQ of 70 or greater have what’s known colloquially as “high functioning” autism, while those with severe-moderate atypicality combined with IQ below 70 are said to have “low-functioning” autism. Persons with Asperger Syndrome are hyperverbal, while persons with autism and PDD-NOS are hypoverbal. The DSM-V will be eliminating all of these individual terms, making it all the more important to describe IQ as well as atypicality when characterizing an individual’s development.(Based on “Making Sense of Autistic Spectrum Disorders,” figure 5.4).
Long-term outcome is driven by the combined effect of degree of atypicality and IQ. In some cases, the person’s atypical features will fade to the point where he or she no longer meets criteria for a diagnosis of ASD. However, this does not mean that such individuals are “cured.”
More on these topics next time. If you want to “read ahead,” view this clip:
The entire webinar, “Autism Spectrum Disorder across the lifespan,” can be viewed here or on my home page.
If a picture is worth ten thousand words, then here’s the picture:
This is a 3-dimensional graph, showing Degree of atypicality on the X axis, IQ on the Y axis, and Age on the Z axis. Over the next couple of posts, I will explain how I created this graph, and why it is important to you, whether you are the parent of a child with ASD, a therapist or educator working with children with ASD, a researcher interested in the epidemiology of ASD or the efficacy of various interventions for ASD, or if you are an individual with ASD yourself.
And if you are uncomfortable with graphs, don’t worry! I have a way to explain what we’re getting into, that won’t require you to use graphs.
In 1886 the beloved American poet Emily Dickenson died of “Bright’s Disease”- the popular term in those days for kidney failure. No one dies of Bright’s Disease these days – Not because kidney failure has been eradicated, but because it has been broken down into dozens of specific disorders, each with its own cause and form of treatment, thereby relegating “Bright’s Disease” to the ranks of discarded medical diagnoses, along with ptomaine poisoning , consumption, and falling sickness. Each of these obsolete diagnoses referred to a specific symptom or set of symptoms (edema, in the case of Bright’s Disease) that was considered the hallmark of the disorder. In each case, however, medical science eventually produced a deeper understanding of the problem: Often, it turned out that a specific biological factor could give rise to many different symptom patterns (or, no symptoms at all, in some individuals). Conversely, sometimes different biological factors produced identical symptoms. Therefore, even though two patients might have identical symptoms their treatments might vary, because of this difference in underlying cause (we don’t give antibiotics to treat viral pneumonia, for example). Eventually, the original, symptom-based diagnoses were discarded, in favor diagnostic formulations based not just on symptoms, but on mechanisms of biological causation. Read the rest of this entry »
All that is necessary for the triumph of evil is for good men to do nothing.
– Edmund Burke Knowledge is power
– Francis Bacon
Each of us also has an obligation to try to leave the world a little better place than we found it. I write, as one way of trying to meet this obligation. Life is a continual struggle between the best and worst in human nature. I write as my way of engaging in that struggle – my way of fighting back against ignorance, superstition, and intolerance. So much for why I write. More importantly, why should you listen?