Most people think that dyslexia causes a person to see words or sentences backwards, or that it causes a person to confuse the letter 'b' with the letter 'd.' This is just one form of dyslexia, known as strephosymbolia.
Dyslexia, also known as developmental reading disorder, affects a person's ability to comprehend either oral or written language and sometimes both. In other words, it is a general, language-related learning disorder. Tasks and activities many of us take for granted, such as writing out a grocery list, reading the newspaper or listening to a book on tape, could be problematic for someone with dyslexia. Recent studies suggest that something like 15 percent to 20 percent of the population has some type of reading disability, and of those people, about 85 percent have a form of dyslexia.[Ref]
Although diseases of the brain can cause dyslexia and other learning disorders such as dyscalculia and dysgraphia (see sidebar), medical research indicates that, for most people, these are the result of a malfunction (not a disease) within the brain. Brain-imaging studies have shown that the brains of dyslexics develop and function differently than those of people who are not dyslexic. Furthermore, dyslexia can be inherited. In many instances, it is discovered that either one or both of a dyslexic child's parents suffer from this learning disorder as well.
Learn about the symptoms of dyslexia on the next page.