About Reading Disorders
CAUSES OF READING PROBLEMS
One of the most common reading disorders in children is developmental dyslexia. Dyslexia is one of the more common conditions to affect school age children. It is estimated that between 5 and 10% of children between the ages of 5 and 20 meet criteria for the reading disorder.
There has been a wealth of information published on this disorder since first conceptualized nearly a hundred years ago. What researchers have essentially concluded is that we don’t have a formal reading center in our brain. Rather, we utilize language and speech areas to make sense of written words. Thus, any disorder that affects language systems can impact reading. In fact, in adult stroke patients, there is an unusual condition called alexia (inability to read) without agraphia (inability to write), which means that a person could write a sentence but be unable to read what they had just written. Through the advent of neuroimaging, we have been able to trace the pathways that lead from the visual perception of written text to the decoding of that text for meaning and have a pretty good understanding of how children with dyslexia read differently than normal children. We have not been as successful in figuring out the cause of this disorder.
The current thinking is that our visual system is built to recognize objects from a variety of different angles because we are creatures that move in the world. For instance, if I turn a chair on its side, it won’t take you long to figure out it is still a chair. However, letters and words need to be identified in the same orientation and in the same order if they are to have meaning. The visual system, therefore, “cheats” by funneling letters and words over to the language centers for processing instead of in typical object recognition centers. If this process occurs correctly, most children will be able to read as early as 5 years of age. If they don’t funnel this information correctly to the left side, they will continue to treat letters and words just like objects in the environment. For instance, a child might see the word “choir” but say the word “chair” since they are visually so similar in appearance. However, their meaning is quite different and clearly comprehension is going to be affected if many of those errors occur.
Some of the common signs of dyslexia in younger children can be the omission of connecting words (i.e., in, an, the, to, etc.), taking the first letter or two of the word and guessing, or converting words that they have never seen into words that they already know, even when the meaning is quite different.
I hear often that parents become worried because their child reverses letters and, while this does occur in children with dyslexia, it is also a fairly common phenomenon with children who are learning to read, particularly with letters that look similar (i.e., b and d). Thus, it often does take a trained professional to differentiate children who are poor readers or who are developing slowly or in a patch-like fashion from children who actually have dyslexia.