What Dorian said is true. Also the staging means a lot in terms of the moving ability. My father-in-law now has trouble walking without a cane. He is slower walking and slow in getting up from his couch after a long day/evening. He is 88 and has stage 6 of AD. When he had early or moderate Alzheimers (stage 1-5), he was able to walk like before and was not idle (up to mid-2007). One could see visible changes of his movements in late 2007 and 2008 when he got worse. (He was also sick at this time.) I would say it is pretty severe or serious when the patient cannot move much anymore. In the end, he/she would need a wheelchair - that is, they would stop walking in stage 7, the end stage.   Nina