For twenty-three years the definition had remained essentially unchanged. On October 22, 2025, the International Dyslexia Association approved a new formulation of dyslexia; the scientific work that explains the reasons and limits was then published on 29 April 2026 in the Annals of Dyslexia. The change touches on some points that may seem technical until they end up in front of a child who reads slowly, gets words wrong and must demonstrate that he or she is in “enough” difficulty to receive help.
The new definition from the International Dyslexia Association describes dyslexia as a specific learning disorder characterized by difficulties in reading words and/or spelling, which may involve accuracy, speed or both. It adds three important elements: difficulties are distributed along a continuum, they also change based on the writing system of the language and can persist even when teaching works for peers.
There was quite a lot of work behind the new text: a steering committee of 18, an advisory committee of 74, a literature review, and over 3,000 submissions received during the public consultation in August 2025. So yes, it took them a long time to even decide how to define the problem. Given what may depend on those words, perhaps that was the case.
IQ ceases to be the guardian of the door
One of the most notable changes concerns general intelligence. The 2002 definition spoke of “unexpected” reading difficulties compared to other cognitive abilities. That passage has disappeared.
A clarification is needed here, because an important simplification is circulating in the reconstructions on the new definition: the 2002 IDA text did not establish a mandatory threshold of 15 points between IQ and reading performance. However, the old formulation recalled the comparison with cognitive abilities and in some contexts favored the use of models based on the discrepancy between IQ and reading performance.
The IDA itself today explains that it has eliminated that reference precisely because the available evidence does not support this way of separating those who are dyslexic from those who “simply” have difficulty reading. Word reading difficulties appear in people with different cognitive profiles, and general intelligence says little about the nature of the problem, its mechanisms, or response to interventions. In the official explanation of the new definition this step is explicitly indicated.
Does this mean that a cognitive test will never again be useful in a clinical evaluation? No. The new definition does not dictate a universal diagnostic protocol and does not establish which tools should be used in each country. It says something more limited: a significant difficulty in reading should not be excluded from dyslexia just because the person’s cognitive profile does not produce the expected discrepancy.
In Italian a child can read just right, but too slowly
Then there is a seemingly harmless word that matters a lot for Italy: “orthography”, understood as the language’s writing system.
English has a particularly irregular correspondence between letters and sounds. Italian, Spanish and Finnish are instead considered more transparent orthographies: the relationship between what you see written and what you pronounce is generally more predictable.
This difference also changes the way dyslexia can manifest itself. The work published in the Annals of Dyslexia reminds us that, in transparent orthographies such as the Italian one, many children soon reach high levels of correctness in reading. Difficulties can then become more visible in the speed, automation and effort required to read, even when a large part of the words are pronounced correctly.
It is a detail that is anything but ornamental. A definition built primarily on English risks looking for the same signals in linguistic systems that function differently. The new version also incorporates studies on Chinese, Japanese, Hebrew and Arabic, where the linguistic units involved in reading still change.
Phonology remains important, without becoming a universal requirement
Even the phonological deficit loses the almost obligatory role it had in the previous formulation.
Difficulties in processing speech sounds remain very frequent in dyslexia, but research shows too great variability to consider them present in all cases. The new definition also adds morphological processing, that is, the ability to recognize and use the significant parts that make up words.
The same authors cite studies in which only about half of the children later identified as dyslexic previously had a significant deficit in phonological awareness. The bond exists and is robust at the group level; it does not function as an individual diagnostic stamp valid for everyone.
The way of describing the causes also changes. The 2002 version spoke of a neurobiological origin. The new one considers together genetic, neurobiological and environmental influences that interact during development. This does not mean attributing dyslexia to the environment or to bad teaching: the document specifies that environmental factors alone are not enough to explain it. They serve to describe a mechanism that is much less linear than the old cause-effect scheme.
Intervene before waiting for a child to fall behind
The last sentence of the new definition is perhaps the one that can produce the most concrete effects: support for language and literacy before and during the first years of school is indicated as particularly effective.
The authors explicitly distance themselves from the so-called “wait to fail” approach, i.e. waiting until the child accumulates enough difficulties to make the problem evident. The diagnosis of dyslexia cannot be made before the start of schooling, they explain, while some risk factors can be identified earlier: early difficulties in oral language or in processing sounds are signs to be evaluated, not sufficient evidence for a diagnosis.
Even during the first year of teaching it can be observed whether difficulties persist and how the child responds to targeted support. The research reviewed by the authors indicates better outcomes when interventions begin in the early stages of learning to read than when they are postponed until later years.
In Italy the new definition does not change the rules from one day to the next
For Italian families, however, there is a boundary to keep clearly visible. The International Dyslexia Association is not an Italian health or legislative authority and its definition does not automatically modify diagnostic criteria, school certifications or measures envisaged for DSA.
In Italy the regulatory reference remains Law 170 of 2010, which describes dyslexia through difficulties in reading correctly and quickly and speaks of DSA which manifest themselves “in the presence of adequate cognitive abilities”. The same law, however, also establishes that the evolution of scientific knowledge must be taken into account when interpreting the definitions.
On a clinical level, there is also the Italian Guideline on the management of Specific Learning Disorders, published in the National Guidelines System of the Istituto Superiore di Sanità, which regulates a much broader context than a single international definition.
The IDA revision, therefore, updates a very influential scientific compass and puts on paper something that research has been showing for years: looking only at a formula, at a single deficit or at English as a universal model leaves out important pieces of dyslexia. For this to really shorten the time between the first difficulties and help, protocols, professionals, training and school are needed. Twenty-three years of research alone does not make a PDP.
