Dyslexia's first definition update since 2002 drops the 15-point IQ gap

The old rule turned on a difference between two scores. According to ScienceAlert, a child's reading score had to sit 15 points below their score on a standardized IQ test, showing reading that was unusually poor for their overall intelligence ^[3]. "There were many children that came close to that definition, but just missed that 15-point difference by one point," said R. Malatesha Joshi, an educational psychologist at Texas A&M University. "Because of that, they were not allowed further help." ^[6] Under that rule, a 14-point gap did not qualify ^[17].

The rule could also miss a second group. A child who scored below par on both reading and IQ showed little gap, and might never have been identified ^[8]. The revision removes IQ testing, and its authors say reading assessments are more useful on their own ^[4]. They also want reading and spelling judged over time, after teaching ^[5].

The text came out of a consultation with more than 15 international experts ^[2]. It is advisory ^[12]. ScienceAlert's report does not include an estimate of how many children the old cutoff kept out, so the size of any widening is unknown. The IQ comparison is built into school practice. "Because the definition emphasized IQ tests so heavily, every state and school has used them to diagnose, and hopefully that will be one of the big changes we see," Joshi said ^[7]. In my view the near-miss children are the likeliest to benefit first, because their reading shortfall has already been measured. That holds only where a state or district rewrites its eligibility rules ^[6][7].

The causes section changed too. The older guidelines called dyslexia "neurobiological in origin", and ScienceAlert reports that this stays, with genetics and environmental influences now added ^[18]. Joshi described the change more strongly. "We have taken out the brain-based content so people don't think there is something wrong with their brain if they cannot read or have dyslexia," he said ^[19]. The two accounts differ on how much of the brain framing remains ^[18][19].

The revision gives more weight to research from countries where English is not the main language ^[9]. English is an outlier in how hard it is to work out spellings and sounds, as "cough", "rough" and "plough" show, and assessment has to allow for that ^[15]. "Since 2002 we have had more research findings on dyslexia in languages like Chinese, Japanese, Hebrew and Arabic," Joshi said ^[16]. Of the International Dyslexia Association's 2002 committee, he said "every one of them is a Caucasian male, with the exception of one woman" ^[13].

Early intervention gets more emphasis, with speech difficulties and late talking listed as possible early indicators ^[10]. "There can be clues that a child has dyslexia before they enter the classroom," Joshi said ^[11]. According to ScienceAlert's summary, neither sign guarantees a child has dyslexia ^[10].