A learning disability is determined when a person has a learning function (such as reading) that is significantly below their overall intelligence level. There must be problems in more than one setting, such as work, school and/or home.
Usually an individual must obtain an IQ score and compare this to scores in different achievement areas, such as reading comprehension, mathematics, reading speed, and other areas. Standardized reading tests and tests to determine underlying cognitive functions, are given, which may help explain the basis of the learning disability.
This kind of testing takes a lot of time. The intelligence battery takes from two to three hours, and the tests to delineate the underlying cognitive processes take about four to five hours, in order to do an adequate job. Reading tests add to this time. Standard LD Testing reports written by the Brain Clinic are kept brief, in order to keep the costs down, and because these reports are likely sufficient for many purposes. Reports for requesting accommodations at school or extended time on standardized tests, however, are more elaborate. Requirements for extended time reports are described on the Extended Time Evaluation/High Stakes Testing Requirements page.
What are the causes of learning disabilities?
This is a big topic, and has occupied some of the best minds in the field for many decades. In truth, there are many possible causes, since the field which concerns itself with problems with learning is very complex.
There are a number of theories, and to some extent, all of them might be true for different people. As in some other kinds of brain disorders, learning disabilities tend to run in families. If one of your family members had a hard time reading, it is likely a few of the children would have had the same problem. In my practice, it is not unusual for a parent to report the same problem! "Hey, I want to do those tests!" some of them say. And occasionally they will go through the same 7 to 8 hour battery, and find out that they too have a learning disability—sometimes just like their child.
About 80 percent of those with slow reading (with at least average intelligence) have a problem with phonological processing. This means that there is a problem with connecting the written word that the person reads with the sound of that word. To many, this seems easy. But to the learning disabled person who has this problem, it is a struggle, especially with harder words.
There is also evidence that the brain in individuals with dyslexia functions differently than in those who are good readers. Two medical doctors at Yale University, Drs. Sally and Bennett Shaywitz, have been doing research and integrating some of the previous research in this area. Their work has illuminated the fact that individuals with dyslexia have a different brain organization, particularly in terms of some aspects of language processing. But is this the case always? Probably not, since dyslexia is determined by multiple factors. It could have to do with visual processing, or phonological processing, attentional problems, and number of other underlying cognitive difficulties.
The field of learning disabilities is a fascinating one, and there are many aspects as to the nature of particular kinds of learning disabilities. Since there are so many aspects that go into what the underlying issues are in learning disorders, it is not surprising that extensive testing is usually needed to define a particular person's problem.