Is It Selective Memory?

My mother has dementia that is getting more progressive. My question is, how do I get my sister to understand that she is not deliberately not remembering things, people or events. I think my sister is in denial of the severity of our Mom's illness. My sister seems to think that she has selected memory - remembering what she wants to and not remembering other things (i.e. our Mom remembers every Friday that she goes to a little part-time job for a few hours). According to my sister she never forgets to be ready to go to work on Fridays, but she can't remember other events that may happen throughout the week. She (my sister) for the life of her cannot understand this issue of selective memory. Maybe you can help me explain to her the curious dimensions of dementia.

The fascinating thing about the dementias is that no two persons experience it in exactly the same way. However, it's generally true that older memories seem stick around longest (to put it very, very simplistically). Thus, I might remember that every Friday I go to my job because I have been doing it every Friday for a long time. I have repeated this task over and over again, so it is rooted pretty strongly in my long-term memory.

On the other hand, when you tell me what's for dinner, this is brand new information. It doesn't belong to any particular unchanging pattern or routine. If I have dementia I am likely to lose this information immediately and ask you again. And again. I won't remember that I asked, or that you answered. The same holds for who might have visited this week, or that I had my hair cut. These are random events and new information, and they are difficult or impossible for me to hold on to. It does no good to try to "remind" me, because there may be no memory stored in my brain for me to retrieve.

This kind of "selective" memory is not by choice. Just about 100 years' of observing people with Alzheimer's and the other related dementias has demonstrated that this is the way the "demented" brain seems to work. "Last in, first out" is a cliché, but it is so true for the memories of most people with dementia classed as "moderate" or worse.

This is why it seems to be so important to establish a regular routine for those with dementia. It is difficult to do at home, where every day has it's own interruptions and small crises, but it really pays to try. In the best dementia specialized facilities, the routine is prescribed down to 15 or 20 minute intervals, and rarely varies. Residents become accustomed to the routine. Even if they can't describe it, they seem to be happier and function better when there are no surprises to cope with.