Is there a way to "slow down" Dementia in elderly by having them work on simple puzzles & build up from there?

This was suggested and highly recommended by a medical istant who works with patients who have this illness. My mother is 82 years old and is suddenly progressing quite rapidly in that direction. Her long term memory seems to be okay based on what she does remember from long ago and can remember some things in detail. The short term memory is the one that is tremendously frustrating her as she at times cannot recollect the conversation we had 2 minutes later. The doctor has already confirmed to us that it is NOT Alzheimer's. Thank you kindly for any feedback or websites you can direct me to reseach to help slow down or delay this progressive aging disease.