Dyslexia is a specific learning difficulty that primarily affects reading and writing. It does not mean a lack of intelligence, lack of interest, or “seeing letters backward.” Its core feature is a persistent difficulty reading accurately and fluently and spelling well, even when the instruction received has been adequate.
Today, dyslexia is understood as a neurodevelopmental disorder included among specific learning disorders.
How many people does it affect?
The average estimated prevalence is 7.1% among schoolchildren aged 6 to 13 years. More cases have also been observed in boys than in girls, although there is considerable variability across studies.
In adults, figures often appear lower, not because dyslexia disappears, but because it has historically been underdiagnosed. This suggests that it is detected more effectively today than it was decades ago.
Does it manifest in the same way across all languages?
Not exactly. Dyslexia occurs across different languages, but it is not always expressed in the same way. In languages with transparent orthographies, such as Spanish, there are usually fewer severe accuracy errors as learning progresses, but difficulties with fluency and spelling may persist. In opaque orthographies, such as English, reading accuracy is often affected for a longer period.
What is the typical profile?
Although every person is different, certain features appear frequently:
- Difficulty decoding and recognizing words quickly and accurately
- Spelling problems
- Weaknesses in phonological processing
- In some cases, difficulties with rapid naming and automatization
An important point: dyslexia is not limited to confusing letters or writing them backward. These reversals may occur in many children at the beginning of literacy instruction. What defines dyslexia is the persistence of reading and writing difficulties and their impact on academic or functional life.
Common comorbidities
Dyslexia often co-occurs with other neurodevelopmental disorders. The most relevant associations are with:
- ADHD
- Developmental language disorder
- Dyscalculia or mathematical difficulties
This is important because when dyslexia is identified, it is also advisable to assess attention, oral language, and mathematical performance in order to better tailor the intervention.
Why does it occur?
Current evidence shows that dyslexia is multifactorial. There is no single cause. Genetic factors, differences in the functioning of brain networks involved in reading, and environmental factors such as instructional quality and access to support all play a role.
In genetics, recent studies point to a polygenic architecture: many small genetic variants contribute to risk rather than there being a single “dyslexia gene.” Associations have also been found with other neurodevelopmental profiles, such as ADHD.
In neuroimaging, differences are usually found in the left-hemisphere reading network, especially in occipitotemporal, temporoparietal, and inferior frontal areas. Even so, these findings help explain group-level trends; they cannot be used to diagnose a specific person through a brain scan.
Which interventions work best?
The strongest evidence supports explicit, systematic, and structured reading instruction. This includes direct work on grapheme-phoneme correspondences, phonological awareness, decoding, guided practice, and ongoing progress monitoring.
Outcomes are generally better when support begins early and has sufficient intensity. By contrast, multisensory programs such as Orton-Gillingham have more uncertain evidence. This does not mean they cannot help, but the method label does not guarantee effectiveness if it is not supported by high-quality instruction.
Prognosis
Dyslexia is usually persistent, but it changes with age. In childhood, decoding and accuracy problems predominate. Later on, many people improve in accuracy but continue to have difficulties with fluency, spelling, reading speed, and academic or work-related demands.
In adulthood, the impact does not disappear: it may affect education, employment, and social participation. For this reason, there is increasing emphasis on lifelong support approaches, not only during the school years.
Warning signs by age
As we have seen, the best response to dyslexia is to act early. Although a definitive diagnosis is usually made at around 7 or 8 years of age (when sufficient reading instruction has been provided), there are early warning signs that allow us to intervene preventively.
These signs vary as the child grows and the demands of the environment change:
Preschool (ages 3 to 5)
At this stage, formal reading instruction has not yet begun, but the foundations of oral language and phonological awareness are being established. Signs to watch for include:
- Delayed speech development or recurring difficulty pronouncing long or unfamiliar words.
- Difficulty learning or remembering nursery rhymes and songs.
- Problems memorizing everyday sequences, such as the days of the week, or rapidly naming colors, numbers, or letters.
- Difficulty breaking words into syllables by clapping.
Early elementary school (ages 6 to 8)
This is the critical stage of literacy instruction, when children face the challenge of decoding. The clearest signs are:
- Persistent difficulty associating a letter with its sound (grapheme-phoneme correspondence).
- Very laborious reading, with frequent pauses, omission errors (skipping letters), or guessing words from context.
- Emergence of reversals (such as confusing “b” and “d” or “p” and “q”). Although these are common in all children at the beginning of learning, in dyslexia these confusions are much more persistent.
- Refusal or anxiety when reading aloud, often accompanied by physical complaints (headache or stomachache) when doing homework.
Upper elementary and middle school (age 9 and older)
At this age, reading is expected to be a tool for learning other subjects. If dyslexia is present, accuracy problems may decrease, but other challenges emerge:
- Slow reading and a lack of fluency, requiring exhausting mental effort.
- Reading comprehension problems, not because of a lack of ability, but because all cognitive resources are consumed by the effort of decoding.
- Very poor and disorganized spelling, even when copying text from a whiteboard or book.
- Significant difficulty learning foreign languages, especially those with opaque orthographies such as English.
- Decline in academic self-esteem, feeling that their effort is not reflected in their grades.
Key points
Dyslexia is not an intelligence problem, but a specific and persistent difficulty with reading and writing. It affects approximately 1 in 14 schoolchildren, although figures vary depending on the criteria used. Its origin is multifactorial, with genetic, neurobiological, and environmental foundations. The best response is not to wait, but to detect it early, teach using evidence-based methods, and provide reasonable and accessible supports.
Dyslexia requires an accurate assessment and an evidence-based structured intervention, especially to adapt treatment to each user’s needs. In this context, digital tools such as NeuronUP Assessment allow professionals to conduct a comprehensive cognitive assessment, identifying difficulties in key processes such as reading, attention, or memory. In addition, the platform facilitates the design of personalized intervention programs, with specific activities targeting phonological awareness, decoding, and reading fluency, thereby optimizing the cognitive rehabilitation process for people with dyslexia.
