Complex sentence: As their AD progresses, so does the severity of their agraphia; they may begin to form spatial agraphia, which is the inability to write in a straight horizontal line, and there are often unnecessary gaps between letters and words.
Split into simpler sentences: As their AD progresses, so does the severity of their agraphia. They begin to form spatial agraphia, which is the inability to write in a straight horizontal line, and there are often unnecessary gaps between letters and words.