What the Research Says About Reading and Dyslexia

By Laura Lurns · Reviewed by Philip Weaver · Last reviewed 2026-10-03

What this page covers

This page opens one of the ten areas in our research section. It reports what the studies we hold found, as strongly as they found it.

This page covers the 2025 dyslexia definition, causes, teaching, early skills, the brain and feelings.

Read what a study does not show before you read what it found.

The 2025 definition

This part covers what the 2025 definition says.

The International Dyslexia Association (IDA) wrote a new definition in 2025. The definition describes trouble reading words or spelling, in accuracy, speed or both. It says the causes are complex. It names "genetic, neurobiological, and environmental influences" that act on each other as a child grows. The definition names no single cause.

The IDA's definition says the trouble lasts even with teaching that works for other children their age. It does not say for how long.

The IDA says trouble with word sounds and word parts is "common but not universal" in dyslexia.

By Catts and colleagues' account (2026), nothing beyond the reading and spelling trouble reliably identifies dyslexia in one child. No scan or gene test does.

Researchers disagree about how common dyslexia is (Catts and colleagues, 2026). Some say as many as one child in five has it (Shaywitz and colleagues, 2021, as reported in Catts and colleagues, 2026). Many others see dyslexia as a more severe condition. They put it at about 5 to 10 in every 100 students (Fletcher and colleagues, 2019, as reported in Catts and colleagues, 2026). The two views draw the line in different places.

Family history, screens and trauma

This part covers family history, screen time and trauma.

One review looked at children whose parent, brother or sister had reading problems. It was by Snowling and Melby-Lervåg (2016). Those children went on to have dyslexia far more often than other children. Many of those children did not go on to have dyslexia.

These are findings about groups of children. They are not a checklist for one child.

No study we hold shows that screen time or trauma causes dyslexia.

Teaching reading

This part covers studies of teaching children to read.

The National Reading Panel found that systematic phonics instruction significantly improves reading achievement.

One review looked at 22 trials of help for children with reading disabilities (Galuschka and colleagues, 2014). Phonics teaching was the only approach it confirmed for reading and spelling. The other approaches had far fewer trials. So their results are partly thin evidence, not proof they do not work.

Reading improves with reading instruction.

One study tutored young children who were behind in reading (Vellutino and colleagues, 1996). Some caught up quickly, and some did not. We could read only its summary. Those findings are about groups of children, not a promise about yours.

One trial looked at young children who gained little from help (Wanzek and Vaughn, 2008). Some then got a single amount of extra help. Some got a double amount, and some got none. Over time, the single and double amounts did about the same. More children who got help made faster progress than children who got none. We could read only its summary. Those findings are about groups of children, not a promise about yours. They are not a reason to wait and see. No study we have tests wait-and-see as a plan for a learning difficulty. So we would not tell you to wait.

Early skills that predict reading

This part covers early skills that predict later reading.

A federal panel looked at studies of children up to age 5 (National Early Literacy Panel, 2008). Six early skills predicted later reading and writing. They did so for children both before and in kindergarten. Knowing letter names and sounds was one of the six. These are findings about groups of children. They are not a checklist for one child. No study we hold makes one of these skills alone a sign of dyslexia.

Reading and the brain

This part covers brain-scan studies of reading teaching.

One study scanned a group of children with reading trouble (Meyler and colleagues, 2008). The children had 100 hours of intensive reading teaching. At first, activity in two left-side areas was well below good readers'. Activity there kept going up after the teaching ended. A year later, the group's average there reached the good readers' level. That is a group average, in two areas of the brain. Those findings are about groups of children, not a promise about yours.

Meyler and colleagues' 2008 study measured brain activity, not the brain's structure. Perdue and colleagues (2022) reviewed 39 imaging studies of reading teaching. The studies do not agree on a set of brain changes. Perdue's pooled analysis found no significant effect. Whatever the scans show, reading improves with reading instruction.

Only one teaching study we hold measured the brain's structure. The change it found tracked only the narrow skill that was taught. A few of the 39 studies in Perdue's review also looked at structure. We know them only through that review. Our rule is that no page says teaching changes the brain's structure.

Reading and feelings

This part covers studies of learning difficulties and feelings.

The studies we hold link learning difficulties with frustration, lower self-esteem and higher anxiety. That is an association, not a cause. Some studies point to support from parents and teachers as something that may help protect against these risks.

These are findings about groups of children. They are not a checklist for one child.

What the reading research we hold does not show

This part covers the limits of the studies on this page.

By Catts and colleagues' account (2026), nothing beyond the reading and spelling trouble reliably identifies dyslexia in one child. No scan or gene test does.

A federal panel looked at studies of children up to age 5 (National Early Literacy Panel, 2008). Six early skills predicted later reading and writing. These are findings about groups of children. They are not a checklist for one child.

The studies we hold link learning difficulties with frustration, lower self-esteem and higher anxiety. That is an association, not a cause. Some studies point to support from parents and teachers as something that may help protect against these risks.

Only one teaching study we hold measured the brain's structure. The change it found tracked only the narrow skill that was taught.

The IDA's definition says the trouble lasts even with teaching that works for other children their age. It does not say for how long. The definition does not review or rate any program, ours included.

Our rule is that no page says how your child will change by a given week or month.

Does Learning Success build on this?

Partly. We use one point from this page. Reading improves with reading instruction. Our reading course is practice on reading and spelling words. It is not practice on a general brain skill. It does not teach comprehension, and it does not replace reading teaching.

Suppose a program shows each word letter by letter. The picture comes only once the word is complete. So guessing from the image is not available. That is a fact about the design.

In no case do we claim a study's result for our program.

No study of any Learning Success program exists.

Questions we plan to answer on later pages

Later pages in this area are planned. None of them is written yet.

• What does the 2025 definition of dyslexia say, and what changed from 2002?
• What limits does the IDA put on its own definition?
• How common is dyslexia, and why do the numbers disagree?
• Practicing a reading skill directly: what was tested, and in whom?
• Which early skills predict later reading, and what can they not tell you?

The studies

• International Dyslexia Association (2025). Definition of dyslexia. Adopted 22 October 2025.
• Catts HW, Haynes CW, Joshi RM (2026). Defining dyslexia: 2025 revision. Annals of Dyslexia. DOI 10.1007/s11881-026-00363-4.
• Shaywitz and colleagues (2021) and Fletcher and colleagues (2019), as reported in Catts and colleagues (2026).
• National Reading Panel (2000). Report of the National Reading Panel: Teaching children to read. NIH Publication No. 00-4769.
• Galuschka K, Ise E, Krick K, Schulte-Körne G (2014). PLoS ONE 9(2):e89900. DOI 10.1371/journal.pone.0089900. Correction: PLoS ONE 9(8):e105843.
• Vellutino, Scanlon, Sipay, Small, Pratt, Chen and Denckla (1996). Journal of Educational Psychology 88(4):601–638. DOI 10.1037/0022-0663.88.4.601.
• Wanzek and Vaughn (2008). Journal of Learning Disabilities 41(2):126–142.
• National Early Literacy Panel (2008). Developing Early Literacy: Report of the National Early Literacy Panel. National Institute for Literacy.
• Snowling MJ, Melby-Lervåg M (2016). Oral language deficits in familial dyslexia: a meta-analysis and review. Psychological Bulletin 142(5):498–545. DOI 10.1037/bul0000037.
• Meyler and colleagues (2008). Neuropsychologia.
• Perdue and colleagues (2022). Neuroscience & Biobehavioral Reviews.