It is very common to have a learning disability together with ADHD. Research shows that thirty percent of people diagnosed with ADHD also have a learning disability. Beyond learning disabilities, over fifty percent of individuals suffering from ADHD have some other type of brain-based disorder; this explains why depression, anxiety, OCD, bipolar disorder and other similar disorders occur at an incidence that is higher than normal in ADD clients.
One type of learning disability that almost every person with ADD will have is an integrative processing deficit. This is the ability to take in information, process it quickly and make use of it. Most people with ADD are either slower than others in performing this process, or have trouble performing it at all; it is not that they do not understand the information, but rather that conflicting signals will make it difficult to fully process it.
Another common learning disability in people suffering with ADHD is working memory problems. Working memory is another term for short term memory, or information that is told to you in the moment. This can affect information you hear, read, etc. Working memory is important for doing well academically and at work.
Another learning disability that is common in individuals with ADHD is problems with visual/spatial processing. This is hardly surprising, since most people with ADHD have problems with organizing space. Academically, this will affect subjects such as geometry and physics.
Other common learning disabilities are dyslexia, reading comprehension, arithmetic reasoning, oral expression, written expression, foreign language acquisition, syntactic processing, and most likely other learning disabilities. Consequently, getting a thorough examination at the start is so important: an individual may be dealing with ADHD, but he or she may also be dealing with a learning disability. And although you cannot directly do anything about a learning disability, it is useful to know that you do have one and be aware of how it affects your ability to function. Furthermore, you may receive academic accommodations and job accommodations if diagnosed with a learning disorder.
In order to find out if you have a learning disability, it will be necessary undergo a lengthy set of tests that compare and contrast your IQ, personality and interests. If you do significantly better on one aspect of a test than another, this could signify a learning disability. For example, if you do really well on the verbal part of your IQ test and not so well on the visual/spatial section of the IQ test, you may be diagnosed as having a learning disability.
It is not known exactly why ADD is often accompanied by some type of learning disability. Most likely, the atypical wiring of an ADD sufferer has something to do with it. New research is presently in progress on the brain and on how it works; science does not yet have all the answers to these questions.