Dyslexia is the most common learning disability in the world, affecting approximately one out of every 20 children. Although it can vary in how severe it is, children and adults with dyslexia have difficulty reading, writing, and spelling, due to their brains struggling with symbols.
Before we came to understand more about dyslexia, people with this disability were often looked down upon by society. The ability to read was thought of as a basic skill that anyone could do, and people who struggled with it often were branded with a stigma of low intelligence. We know now that this is not the case at all. People with dyslexia are often just as intelligent as their peers; they just have a reading disorder that makes it harder for them to correctly process the written word.
Causes
Science has not yet determined exactly what causes dyslexia. We do know that it tends to run in families. Children who are dyslexic are likely to have an older relative who is also dyslexic. This leads many to assume that it is a genetic disorder, passed down from parents to children in their DNA.
Some studies have been able to pinpoint differences in the brains of dyslexic children. Specifically, they have found that people with dyslexia have difficulties linking words and letters with the sounds that they make. Their memory of the written word is poor, but, perhaps surprisingly, their memory of the spoken word is poor as well. This means that dyslexia may present itself very early in life, even before a child has been taught to read. A child may talk late, have trouble learning new words, and struggle with instructions that take several steps.
Testing
Although we know that there are differences in the brains of dyslexic people, scientists don't know exactly what causes those differences. Because of this, there is no medical test in place to determine if a child is dyslexic. The process for diagnosing dyslexia consists of a doctor administering reading tests or skill tests and analyzing the child's behavior and performance, as opposed to the blood tests or brain scans that other medical diagnoses might require.
Risk Factors
Because the definitive cause of dyslexia is still unknown, there are few known risk factors. The only truly known risk factor is the genetic one, where other adults in the family have the same learning disability. If nobody on either side of a couple's family is dyslexic, there is less of a chance that their child will be.
It used to be thought that dyslexia was tied to poor vision and that children facing reading obstacles were having trouble literally seeing the letters. Current research on dyslexia, however, indicates that it is not linked to a child's eyesight at all; poor vision is not considered a risk factor.
