I've worked with people who have developed Alzheimer's disease, and as you can imagine, it is not pleasant at all for the unfortunate individual who suffers from it.
William Utermohlen was diagnosed with it in 1995, and decided to do self portraits as it progressed, to document the way it affected himself, both in his ability to capture his own image, and his perception of that image.
The results are above. The first self portrait is from 1967, but the rest are from 1996 to 2000. William died in 2007.
More information can be found here.