Dyslexia

What Causes Dyslexia?

While scientists have a good idea of which parts of the brain are affected by dyslexia, it’s not yet clear what’s going wrong in those areas of a dyslexic’s brain. The uncertainty makes it challenging to find the cause (or causes) of the disorders.

Although researchers have not discovered what causes dyslexia, they know some things that don’t cause it. People with dyslexia do not have vision or hearing problems that make them unable to see or hear language correctly, and there is no other physical trigger for the disorder. Dyslexia is also not part of a bigger cognitive problem; people with dyslexia don’t have below-average intelligence, and some have above-average intelligence.

The root of the disorder seems to lie in a problem that surfaces while a child’s brain develops early on. The cause of the developmental abnormality remains unknown, but a few risk factors seem to play a role.

• Family history. Children with a family history of dyslexia are at increased risk of having the disorder themselves.
• Low birth weight
• Exposure of the mother to nicotine, alcohol, or other toxins during pregnancy

Is Dyslexia Hereditary?

Children who have a history of dyslexia in their families have a much greater risk than the general population of having the disorder. Studies have demonstrated that a child whose parent has dyslexia has between a 40% and 60% chance of being dyslexic.

Environmental factors could play a role in the prevalence of dyslexia within families. Still, studies of identical twins–who are genetically identical to one another–suggest that genetic similarities are at least part of the reason for increased risk in some families.

Researchers have not yet been able to determine which genes or gene variants might contribute to the risk of developing dyslexia. Studies have narrowed the possibilities to a handful of likely culprits. The process of neurological development that results in dyslexia is complex, however, and, likely, there is not a single genetic cause for the disorder. It’s more likely that an interplay of multiple genes and environmental factors is to blame.

How Is Dyslexia Detected?

The learning problems caused by dyslexia are most often noticed when they begin to interfere with a child’s schoolwork, but some signs may be apparent much earlier. Early detection of the disorder can help the child learn to cope and ensure that they get adequate support at home and school from the very beginning. Dyslexic children who get support when they are in kindergarten or before are more likely to perform better later.

In general, the earliest signs of dyslexia surface in the areas of language development. Warning signs include:

• Starting to speak later than usual
• Difficulty in learning new words once speech begins
• Confusing words (especially those that sound alike)
• Mixing up sounds when pronouncing words
• Difficulty remembering the words to songs or rhymes

How Is Dyslexia Diagnosed?

Dyslexia doesn’t have a physical cause, so no physical exam or laboratory test can detect the disorder. Instead, a doctor will focus on assessments of a child’s developmental and educational performance to determine whether the child’s symptoms are consistent with dyslexia. There will also probably be an effort to rule out other possible causes for the symptoms.

• Developmental history. Your healthcare provider will ask questions about your child’s language development and current language skills. They will also ask about the child’s medical history to rule out other health factors that could contribute to the symptoms.
• Family history. The provider will look for a family history of dyslexia and other environmental factors that could be significant.
• Physical and neurological exams. These exams will check the child’s vision, hearing, and neurological functions to rule out physical problems other than dyslexia that could be causing the symptoms.
• Psychological assessments. The provider may also administer exams or questionnaires meant to rule out psychological conditions such as depression or anxiety that could be responsible for learning difficulties.
• Cognitive and educational assessments. These exams and questionnaires will be aimed at accurately assessing the child’s language and reading skills to pinpoint exactly where the learning difficulties lie.

How Is Dyslexia Treated?

There is no known way to change a dyslexic brain to make language processing difficulties go away. Treatment is instead focused on helping the sufferer to compensate for the language disability to minimize its impact. For the most part, the disorder is treated by developing educational plans that support the dyslexic’s skills. Different individuals respond to different approaches, so individualized education plans are essential.

Some common treatment approaches include:

• Using other senses, such as hearing or touch, to support the child’s language-learning skills
• Teaching the child to recognize the smallest components of written language better so that word-recognition skills can improve
• Using out-loud reading to improve the child’s language-processing skills
• Focusing on vocabulary building so the child has a broader range of reliably recognizable words

How Does Dyslexia Progress?

When dyslexia goes undiagnosed and untreated, difficulties with language processing can interfere in many other learning areas, leading to escalating and long-lasting developmental and social problems.

Long-term complications of dyslexia can include:

• Broad learning difficulties. When a child has trouble reading, they are likely to have trouble with most other academic pursuits.
• Social difficulties. Problems with learning can harm other aspects of a child’s life, too. If the child lags behind their peers academically, they can be vulnerable to depression, anxiety, bullying, and social isolation.
• Life-long consequences. Language-processing struggles can impact adults, too. Learning difficulties can hinder an adult’s career prospects, and ongoing language problems can get in the way of job performance. The result can be long-term financial and social challenges.

How Is Dyslexia Prevented?

Just as there’s no known cure for or cause of dyslexia, there is no known way to prevent the disorder. However, parents of a dyslexic child can take steps to support the child’s early learning and hopefully limit the negative impact of the condition in the future.

• Look for warning signs and seek help early. Early detection and treatment of dyslexia is the single most significant factor in the effective management of the disorder.
• Start reading aloud to the child very early on. Read to the child as an infant, and continue to read throughout their childhood. Consistent reading may help to foster better language-processing abilities.
• Support, encourage, and facilitate the child’s reading. Make reading a routine part of the child’s life, and do everything possible to make reading a pleasant experience.
• Make sure the child is getting support at school. Work with the school to develop an individualized educational plan, and remain involved as the plan is carried out.

Dyslexia Caregiver Tips

Dyslexia affects children when they’re still too young to comprehend the effects of the disorder. Therefore, it’s up to their parent and caregivers to be sure the condition is treated appropriately. Keep these tips in mind as your child enters school and confronts the consequences of the disorder.

• Be positive and encouraging. Dyslexia can have a brutal impact on a child’s self-esteem. Make sure your child knows that dyslexia isn’t a sign of low intelligence. Focus on the child’s skills and strengths instead of on their difficulties.
• Be supportive of your child’s educational goals. Structure your home life so that your child has a quiet, distraction-free place and time to study. Make reading and studying a regular part of the day, and place limits on technology and other distracting activities.
• Be involved with your child’s school. Your child needs to get support from professional educators at school, but it’s also essential for you to advocate for your child. Be aware of how your child’s educational plan is progressing, and don’t hesitate to express any concerns you may have.

Many people with dyslexia also suffer from other brain-related issues, a condition called co-morbidity. Here are a few of the disorders commonly associated with dyslexia:

• Coordination disorders such as developmental dyspraxia are sometimes associated with dyslexia.
• People with dyslexia often also exhibit attention-deficit/hyperactivity disorder (ADHD).
• Behavioral problems such as conduct disorder and oppositional defiant disorder are commonly associated with dyslexia.

Dyslexia Brain Science

To try to understand the neurological basis of dyslexia better, researchers have used an imaging technology called functional magnetic resonance imaging (fMRI) to produce a visual representation of brain activity. An fMRI scan uses a magnetic field to make an image that shows activity patterns in different parts of the brain. fMRI studies show a consistent difference in brain activity in dyslexic subjects compared to that in subjects without dyslexia. The studies have pinpointed the parts of the brain affected by the disorder, and fMRI research has also suggested that there may be two types of dyslexia, one genetically triggered and one caused by environmental factors.

Other studies have tried to discover precisely what’s going wrong in the parts of the brain affected by dyslexia. One suspected possibility is that dyslexic brains are unable to produce adequate amounts of a chemical called acetylcholine. This chemical is a neurotransmitter, a compound that helps brain nerve cells function and communicate with each other. A deficiency of this chemical (or some other neurotransmitter) might help to explain why connections between language processing centers in a dyslexic’s brain don’t function properly.

Dyslexia Research

Title: Neural Mechanisms of Successful Intervention in Children With Dyslexia

Stage: Recruiting

Principal investigator: Jason Yeatman, PhD

Stanford University

Stanford, CA

Dyslexia, an impairment in accurate or fluent word recognition, is the most common learning disability affecting roughly ten percent of children. This proposal capitalizes on cutting-edge neuroimaging methods, in combination with reading education programs, to generate a new understanding of how successful reading education shapes the development of the brain circuits that support skilled reading. A deeper understanding of the mechanisms of successful remediation of dyslexia, and individual differences in learning, will pave the way for personalized approaches to dyslexia treatment. 

Title: Effects of TBS on Reading in Adult Struggling Readers

Stage: Recruiting

Principal investigator: C. Nikki Arrington, PhD

Center for Advanced Brain Imaging

Atlanta, GA

The purpose of this project is to understand how reading is related to brain function. To accomplish this, participants will perform some reading tasks and then have magnetic resonance imaging (MRI) brain scans. Participants will then receive transcranial magnetic stimulation (TMS) to the reading areas of the brain, followed by a second MRI brain scan. This will temporarily activate reading abilities. The goal is to better understand how the reading system in the brain functions.

 Title: Improving Response to Intervention in Students With or at Risk of Reading Disabilities

Stage: Recruiting

Contact: Jennifer Shearon

Vanderbilt University

Nashville, TN

The purpose of the proposed studies is to examine a reading intervention for fourth-grade students with reading difficulties that integrate work in mindset (beliefs about whether abilities are innate or can be developed) with the academic component of reading. Specifically, the investigators will examine the extent to which integrating mindset intervention improves student response to reading intervention. The investigators will use previous Research in intensive reading intervention for students with reading difficulties in the upper elementary grades to examine an intervention that addresses reading skill deficits, while also providing mindset training along with (Study 1) or embedded in (Study 2) the reading intervention. It is hypothesized that students in the reading intervention with mindset conditions will improve their reading outcomes more than students in the reading intervention only and business as usual groups.