Brain Development Signals Reading Challenges Long Before Kindergarten
Developmental trajectories of children with and without reading disabilities start to diverge around 18 months, rather than at 5 or 6 years old.
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Given the complexity of the process, it鈥檚 astonishing any human has ever mastered the ability to read. Although written language is ancient 鈥 we鈥檝e been at it for roughly 5,000 years 鈥 it鈥檚 not an innate skill. There is no 鈥渞eading center鈥 in the brain; human brains aren鈥檛 designed to automatically decipher the symbols on a page that add up to reading.
And yet, shows that the skills needed for reading begin developing before a child is born, and that signs of reading challenges can emerge as early as 18 months old.
鈥淧eople don鈥檛 understand that children don鈥檛 start kindergarten with a clean slate,鈥 said Nadine Gaab, an associate professor at the Harvard School of Education involved in the research. Learning to read 鈥渋s a long process with many milestones that unfold over many years, and it starts primarily with oral language. Years of brain development lead up to the point where formal instruction puts it all together and enables them to read. The process starts in utero.鈥
The human brain evolved specifically for spoken language, said Perri Klass, professor of journalism and pediatrics at New York University and the national medical director of the nonprofit . Every society across the world uses spoken language, but the transition from spoken to written language is a giant leap for the brain.
That jump, Klass said, requires the brain to recruit structures and networks throughout its many layers and folds just to recognize a letter on a page, involving the vision and memory portions of the brain. The brain then must remember the sound the letter represents and connect that letter with others to make sounds that associate with the picture on a page. Finally, at lightning speed, the brain recognizes that those letters work together to say, 鈥淐at.鈥
People don鈥檛 understand that children don鈥檛 start kindergarten with a clean slate.
Nadine Gaab, an associate professor at the Harvard School of Education
鈥淟earning to read is a challenge for all children,鈥 she said. 鈥淎nd for some children it鈥檚 really a struggle. It鈥檚 not that you develop spoken language and then, boom, you get to school and develop written language. Spoken and written language have been developing together directly from birth, and all the exposure to language from the environment 鈥 what they hear from their parents, whether they鈥檙e read to, talked to, whether someone sings to them or holds them 鈥 are there. So, it鈥檚 the brain the child takes to school that helps them succeed at this impressive task of learning to read.鈥
Klass points to the new Harvard research to underscore how early that 鈥渂rain the child takes to school鈥 begins developing. For years, a prevailing attitude has been that a child starts learning to read in pre-K or kindergarten. A longitudinal study by Gaab and her colleagues using MRI scans and an array of other assessments confirmed that the bases for reading skills begin to develop in the child鈥檚 brain by birth and continue building between infancy and preschool.
鈥淲e wanted to see how early the developmental trajectories of children who later develop good versus poor reading skills diverge, because that can give us a really important clue for when we should intervene, as well as what some of the risks and protective factors are,鈥 Gaab said,
A key finding of the study is that the developmental trajectories of children with and without reading disabilities start to diverge around 18 months, rather than at 5 or 6 years old as previously assumed.
And yet, Gaab said, a wide gap currently stands between the time children are identified as having a reading impairment and the start of intensive intervention. This is particularly problematic for children diagnosed with dyslexia, she said, adding that researchers call this the The majority of school districts in the U.S. employ a 鈥渨ait-to-fail鈥 approach, meaning that many children are only flagged by the school system after they have failed to learn to read over a prolonged period of time 鈥 often years 鈥 even though there鈥檚 evidence that reading intervention is most effective earlier. The experience of failure can erode self-esteem, she said, and lead to the higher rates of anxiety and depression that are found in struggling readers.
The Study
The study, 鈥淟ongitudinal Trajectories of Brain Development from Infancy to School Age and Their Relationship with Literacy Development,鈥 is the first to track brain development from infancy to childhood focused literacy skills 鈥 a window into later academic attainment.
Over a decade, Gaab and co-authors Ted Turesky, Elizabeth Escalante and Megan Loh conducted MRI brain scans of 130 study participants starting at 3 months old. Half of the children had a risk of dyslexia, with either an older sibling or one or both parents diagnosed with dyslexia, which can increase a child鈥檚 risk of reading challenges. For the first year of the study, the babies peacefully slept through the scan, tucked into the MRI machine wearing noise protection (鈥淲e got really good at putting other people鈥檚 babies to sleep,鈥 Gaab said).

At 18 months old, the babies came back for another scan, though 鈥減eacefully sleeping鈥 was becoming a fond memory. By the time the babies were toddlers, the researchers took a break, for reasons any parent of unruly toddlers can understand. The children returned when they were a more cooperative 4 years old and every year after until age 10.
The study also assessed such factors as cognitive abilities, literacy environment and home language. Funded by the NIH, the researchers aimed to continue for another five years and follow the participants into high school. Though the grant application had received a fundable score at NIH, future funding is uncertain due to the Trump administration鈥檚 termination of .
Building the Brain鈥檚 Architecture
Babies are born with the raw material they need to hear, see, move and remember. The nerve fibers, or axons, that connect these disparate brain regions don鈥檛 grow automatically. They are cultivated by babies鈥 environments. MRIs of the participants as infants showed predictably smaller brains that appear more solid or smooth in the images. By the time the children were 5, the scans showed a robust network of branching pathways of these nerve fibers, said coauthor Turesky.
鈥淭he infant brain is very different compared to all other stages of life,鈥 he said. 鈥淏ut if you look at the scan of a child at 5 years and then at 10 years, you can see there鈥檚 hardly any change in [those pathways]. Those early years are a time of very rapid growth.鈥

Though the human brain remains plastic and mutable for a lifetime, Turesky said, the scans underscore that earliest years are the busiest for building brain architecture 鈥 a fact that has important policy implications for early intervention and improved literacy curricula in preschools.
Giving Them the 鈥楪ood Stuff鈥
Some brains are better equipped to build the neural scaffolding that ultimately leads to reading, Gaab said, and some brains are less optimized, which means those children might struggle to read. It doesn鈥檛 mean their brains are faulty, or that there is something seriously wrong with them.
鈥淭hey鈥檙e built differently, and they鈥檙e optimized for other things, because every brain is different,鈥 she said. 鈥淏ut it does point to the need for good early pre-reading instruction and the games and good oral language input, and home and school environment interactions that we know build these connections. Some brains just need more of the good stuff.鈥
鈥淐all it preventative education, just like preventative medicine,鈥 she said. 鈥淗elp these kids build these connections before they struggle and prevent them ever seeing a special educator or ever getting a dyslexia diagnosis.鈥 A large number of studies now show that early intervention and prevention are leading to better outcomes for children at risk of dyslexia, Gaab said, and the research has led to aimed at early identification and intervention.
That includes teaching the specific skills that can close the gap between proficient and struggling readers. Those skills include phonological awareness, letter-sound knowledge, rapid automatized naming, vocabulary and oral language comprehension. This teaching takes place naturally when caregivers read aloud to their children. Reach Out and Read, the nonprofit Klass leads, has a network of clinicians who work directly with pediatric care providers to help them integrate read-aloud experiences into their interactions with parents and provides developmentally appropriate books for caregivers to take home.
鈥淥ur tremendous advantage in pediatric primary care is that the clinicians see the children over and over in these early years,鈥 Klass said. 鈥淲e see them for a newborn visit and a one-month, a two-month visit 鈥 The schedule is sort of engraved on all our hearts, so we get to talk with the parents about reading and early literacy repeatedly during those early years of life.
鈥淲e know that the developing brain is shaped most of all by the interactions with the adults taking care of that child, Klass said. 鈥淭he wonderful thing about this study is that it literally looks at the building of the brain and says very clearly that it鈥檚 not just that the brain is being built, but the specific structures that will allow the child to read.鈥
If doctors can identify young children who are going to struggle more with learning to read as they get older, they can target those families with books and other support early on, Klass added.
鈥淲e鈥檙e hoping with鈥he books the caregivers are taking home, the child is learning a motivational lesson: 鈥業 like books. If I carry a book and give it to my parent, they might sit down and talk to me in that voice,鈥欌 Klass said.
Klass said no one needs to tell parents to 鈥渢each鈥 this idea to their children. The children will sort it out if they grow up around books and reading. A baby doesn鈥檛 want or need an authority on literacy to walk through the door and teach them how to read, Klass said. A baby wants their parent鈥檚 voice, presence and back-and-forth interactions.
鈥淵our baby wants to be on your lap hearing you read. Your baby will love books because your baby loves you.鈥
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