Dyslexia is offer characterized by the child or adult's struggle with reading and writing. There are a few explanations of what causes dyslexia. According to the experts, there are three main types of dyslexia, categorized by what caused them: trauma dyslexia, primary dyslexia and developmental dyslexia. Some children have dysnemkinetic dyslexia. They are unable to write down symbols, letters or words because these do not have a firm memory imprint in their brain.