In the decades before autism was officially recognized and diagnosed, most autistic patients were relegated to the general diagnosis of mental retardation or, in milder cases, learning disabled.
But the true links between autism and intelligence are more complicated and much more fascinating.
Today, autism is considered a separate disability from intellectual disability, which is the category assigned to anyone with an IQ at or below 70. Among the general population, intellectual disability rates run at about 1 percent; among ASD (Autism Spectrum Disorder) patients, the rate is closer to 40 percent according to the Center for Autism Research.
In addition to having a much higher correlation, there is a lot of speculation that the two conditions may have a causative relationship. Contributing to this belief is the fact that there are well-established connections between other genetic syndromes and intellectual disability – Fragile X, Rett’s, and Down’s Syndrome, among others.
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However, establishing these numbers and correlations is complicated because the standard methods of IQ testing are not necessarily effective with autistic individuals. A 2011 study looking into these issues concluded that the links between autism and intellectual disability were less common than had been historically assumed.
In fact, when autism was first diagnosed, the link between the disorder and intellectual disability was actually called into question. Leo Kanner, the Johns Hopkins’ psychiatrist who is credited with first describing the condition, did so in part because he suspected that the social and communication difficulties of some of his patients were masking their true intelligence as assessed by standard measures.
Modern IQ tests are more accurate and may make use of techniques to assess intelligence without inadvertently being thrown off by autism symptoms. The Test of Nonverbal Intelligence (TONI), for example, allows psychologists to make an assessment of individuals who may have motor and language skill difficulties.
But the jury is still out on whether or not autism itself contributes to intellectual disabilities.
Autism Is Also Associated With Genius
In fact, there is almost as much evidence that the correlation could be in the opposite direction.
There have been theories about underlying connections between autism and intelligence for years. The stereotypes of the mad professor or the eccentric genius are old ones, and some modern psychologists theorize that illustrious scientists such as Isaac Newton and Albert Einstein might have been autistic.
In 2015, Cambridge University undertook a study of almost half a million people and uncovered intriguing evidence that autistic traits (although not necessarily full-blown autism) are more common among people involved in the science, technology, engineering, and math (STEM) fields… careers historically requiring quite a lot of brainpower.
This doesn’t prove any connection between autism and intelligence, let alone a causative one, but other research has gone further. Another study that same year uncovered a likely genetic link between autism and genius—families that were more likely to produce autistic children were also more likely to produce geniuses.
This trend may be under-recognized in the ASD population, according to a 2015 study that found that, while low-IQ ASD patients performed the worst in cognitive function tests, high-IQ ASD patients performed worse relative to a non-autistic control group. The study concluded that different cognitive processes could be affected in high-IQ individuals with ASD, potentially creating the likelihood that their intelligence is further underrated on standard tests.
Differences In Brain Structure Produce Different Outcomes
In one sense, it should be no great surprise that a disability arising from fundamental differences in brain structure, such as ASD, could correlate to another quality based on brain structure. Yet it continues to be mysterious that one syndrome could result in such radically different outcomes in different patients.
MRI investigations comparing the brains of ASD patients to neurotypical control groups unearth any number of differences in activity within the areas of the brain commonly used for social communication and restricted and repetitive behaviors. In the case of autistic savants, those areas are apparently repurposed to perform other feats of intelligence.
Understanding why this happens in some cases but not others is simply another line of inquiry in attempts to understand the mechanisms of autism. It should not, however, be something that therapists or families working with autistic patients should become obsessed with.
More and more research is showing that ASD patients are closer to a normal range in both respects than was previously thought. Dealing with each patient as an individual, with their own capabilities and deficiencies, is the core of the functional behavior assessments used by applied behavior analysts to assess behavior deficits and develop treatment plans. In time, the appropriate therapies may prove to both expose and help develop the underlying intelligence of ASD patients.