Dyslexia is a learning disability that affects a person’s ability to read. But it has nothing to do with reduced intelligence, lack of motivation, or poor eyesight. Rudolf Berlin, the 19th-century German ophthalmologist who first named this condition in his young patients, could find nothing wrong with their vision and speculated that the problem must have to do with the anatomy of the brain. (1) And that’s what scientists now believe: The structure of brain, along with genetics, probably leads a person to develop dyslexia. The National Institute of Neurological Disorders and Stroke defines dyslexia as a learning disability that specifically impairs a person’s ability to read, despite their level of intelligence. (2) Dyslexia isn’t caused by low IQ or low income, and it’s not the fault of the person with the disorder. Indeed, it’s possible for people with dyslexia to be quite gifted. Many celebrated actors, musicians, and artists have had the condition. According to the International Dyslexia Association, signs of giftedness in dyslexia may include: (3)
Superior oral vocabularyCuriosityExpansive imaginationHigh levels of creativityWide range of interests outside of school
In a 2022 study of over 1.5 million adults, scientists have even identified 42 genetic variants strongly associated with dyslexia. (5) Researchers have also noticed that those with a family history of dyslexia tend to have difficulty acquiring and using language as infants and toddlers. (6) But this doesn’t mean absolutely that your child will develop dyslexia if you have the condition, or that your daughter will absolutely develop it if your son has it. It just means that the risk of it occurring is higher than if there were no dyslexia in your family history. Brain imaging studies have shown that there are several regions in the brain’s left hemisphere that are implicated in the visual and aural processes of reading. (8) When regions of the brain work together to accomplish a task or perform a function, neurologists refer to this as a neural network. There’s a neural network that’s involved in processing sounds and images so that a person can read, either out loud or silently, and it involves these left-hemisphere regions:
Occipito-temporalTemporo-parietalInferior frontal cortices (inferior here refers to its anatomical position)
In the brains of those with dyslexia, neurologists have noticed reduced activity and reduced gray matter in these left-hemisphere regions of the brain. (9) But with the correct interventions, the brain is capable of change. According to the International Dyslexia Association, brain imaging studies performed on individuals with dyslexia showed changes after they received reading instruction. (8) Researchers think that effective interventions may lead to lasting positive changes in the brain. (10) The following stressors to fetal or infant health may lead to dyslexia: (11,12)
Premature birthLow birth weightExposure to drugs, alcohol, or nicotine while in the wombInfectionsInfant oxygen deprivationMaternal high blood pressure
Researchers also think that environmental stressors like poor diet or exposure to toxins in water or paint may also contribute to the development of learning disorders. (14) While there is no cure for dyslexia, if you’re pregnant, making sure that you stay as healthy as you can won’t just help you, it may help protect your child against developing the condition. If you’re pregnant or thinking about becoming pregnant, stopping smoking may be the best thing you can do. Acquired dyslexia occurs in individuals who have suffered migraines, or injuries to the brain through strokes or other trauma. (15) A more technical term for acquired dyslexia is alexia. While scientists do not think that developmental dyslexia causes neurological disorders like Alzheimer’s disease, they have noticed an association between learning disabilities like dyslexia and symptoms of atypical dementia (dementia that doesn’t lead to Alzheimer’s disease). (16,17) According to researchers, about one in five individuals with a learning disability who are older than 65 will go on to develop dementia. (18) The notion that more boys than girls have dyslexia comes from what researchers think is a gender bias — meaning that because of cultural gender scripts and expectations, rather than innate biological and psychological differences, boys may be loud when they confront challenges where girls may go quiet. Researchers think that boys have been tested more for reading disabilities and dyslexia because they’re more likely to act out in class when they become frustrated with their work. Because girls with dyslexia tend not to act out but hide their difficulties, it may take longer for teachers and parents to notice reading difficulties in girls. (20) Unfortunately, this often results in many girls getting a late diagnosis.
