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Clinicians make mistakes about intellectual impairments – as new Rett syndrome findings show

Rett syndrome affects one in 10,000 girls. Nadya Eugene

Intelligence is a difficult thing to measure. While IQ tests have been heavily criticised over the last 30 years, society still sets much store by them. Health and education professionals’ decisions about what placements and interventions are appropriate for disabled children are still informed by the child’s IQ score, for example.

This is paradoxical since if you can’t speak or use your hands, it’s impossible to do these tests. Severely disabled children score very poorly regardless of their ability. Even Stephen Hawking would have been categorised as severely intellectually disabled by this measure.

A growing movement in special education and speech/language therapy has recently been urging practitioners to set aside test scores and “presume competence” in people with severe disabilities – meaning you assume an individual is competent in the absence of good evidence to the contrary. They point to growing signs that the abilities of some children have been grossly underestimated.

Recent developments in Rett syndrome are a case in point. Rett is a severely disabling neurological condition which affects around one in 10,000 girls (and far fewer boys). Several new research papers have found that by testing the intelligence of Rett children in other ways than IQ tests, they turn out to be much more capable than previously believed.

Rett and wrongs

Babies with Rett syndrome appear to develop normally at first, but start to regress at around six to 18 months. Most children are left unable to talk or use their hands. Children who have learned to walk before the onset of regression become unsteady on their feet and many stop walking altogether. Most experience problems with their breathing and seizures are common. The condition requires life-long, round-the-clock care.

The traditional assumption is that these children are severely intellectually disabled. When NBC News chief foreign correspondent Richard Engel’s son Henry was recently diagnosed, for example, Engel was told:

It’s not just that he likely won’t walk or talk and may be confined to a wheelchair … he won’t understand what a wheelchair is, let alone how to operate it.

This view has long been at odds with what parents, including ourselves, observe in our children. Parents often report that their child appears to show a considerable understanding of language, makes appropriate and intense eye contact and seems to communicate their intentions by looking in the direction of what they have in mind – known as eye-pointing.

Advances in technology over the past ten years have begun to use this eye-pointing to help people with Rett or other profoundly disabling conditions like late-stage motor neurons disease or cerebral palsy to make choices and communicate independently. Using a system known as eye gaze, they can now control computers by looking at particular items on a screen; this is detected by the computer through a series of lights and cameras.

Latest findings

Researchers have recently used eye gaze to challenge the old assumptions about Rett children’s intellectual abilities. In one study, a team in Tel Aviv modified a standard vocabulary test, the Peabody Picture Vocabulary Test version 4, for a group of 17 girls with Rett.

In a normal Peabody test, children are given sets of four pictures and asked to point to the one that best illustrates a word spoken by the examiner. In the modified version, the four pictures were displayed on a computer screen and the children indicated their response by looking at them.

Remarkably, almost a third of the girls showed a vocabulary at a level indicative of either mild intellectual impairment or even within the normal range.

In a second US study, researchers at the Boston Children’s Hospital tested 47 girls with Rett using another standardised test of ability, the Mullen Scales of Early Learning, which tests children’s developmental progress across the board.

The girls performed predictably poorly on the fine motor and expressive language elements of the test. But again using eye gaze, for the elements that assessed understanding, they showed a wide range of scores. While some showed severe impairment, others were well within the normal range. Children diagnosed with milder Rett syndrome and without a history of seizures typically performed better.

Are the results a good indication of intelligence? Certainly when you look at the testing protocols used by the researchers, it seems unlikely that they overestimated the children’s abilities.

On the other hand, they may have underestimated them. Eye gaze is not an easy technique to master: not all the girls were used to the technology, and they were being measured against scales developed using children who weren’t dealing with any kind of added complication. And when people caring for Rett girls presume the child is severely intellectually disabled, they probably don’t expose them to language in the same way they would a “normal” child.

These results have profound implications for the future of people with this syndrome – and for the debate about presumed competence. If Rett children are only mildly intellectually impaired or even within the normal range of intelligence, it’s necessary to urgently revisit how they are supported and educated. Eye gaze technology promises to be the key to unlocking their potential.

It underlines the importance of presuming competence in people whose intellectual abilities may be unclear – this feeds into previous revelations about the intellectual capabilities of some people with locked-in syndrome, to which Rett syndrome is sometimes compared.

Without presuming competence, even people as gifted as Stephen Hawking may be deemed intellectually disabled. Not only does this have severe consequences for the individual, the loss to society could be nothing short of galactic.

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