Clearing Up Some Confusing Terms

Alexia and agraphia: These terms describe disorders of reading and writing respectively.      The reading impairment may include the ability to read aloud or for understanding (comprehension).  The writing impairment may include the ability to spell correctly or write the correct letters.  When patients have impaired reading and writing, they have alexia and agraphia.  The simultaneous occurrence of these two disorders is more likely in patients with stroke than in patients with Alzheimer’s disease.

Acalculia: This describes an impairment of ability to do mathematics.  When patients are making errors on their check books or do not know how much change they should be getting when they go to the store, they are demonstrating acalculia.

Spatial disorientation: This is an impairment in the understanding of relationships in space.  When patients cannot figure out where there rooms are located or where known locations are when they are traveling, they are demonstrating spatial disorientation.

At this point, I would like to make a couple of comments.  Many of you who have read the above descriptions carefully, may have noticed that many of these terms describe conditions that may overlap with other terms.  Examples include the possibility that spatial disorientation (getting lost) might occur due to spatial amnesia (not remembering what things look like) and that reading, writing and speech are strongly related.  Pure alexia (impaired reading without any other disturbance), pure agraphia (impaired writing), and pure anomia (impaired ability to name) all exist.  However, the most likely situation is for two or three of these to occur together.

Also, many of you may know that the prefix “dys” may also be used with the word roots discussed here.  The use of the prefix “dys” rather than “a.” reflects a convention.  The convention is that “dys” is used to indicate a problem from birth, (i.e., dyslexia is trouble reading because of a developmental problem) and “a” is used to indicate a problem that came on after birth (i.e. alexia is trouble reading because of a brain injury, such as stroke, Alzheimer’s disease, or traumatic injury).

I have addressed some of the more common terms that you might hear in discussions or read in reports about Alzheimer’s disease and patients with it.  It is hoped that this discussion will enable you to better appreciate what is being said or written.