What are the most helpful books you have read on dementia?

Dad has dementia (but not Alzheimer) which is the result of damage to his brain from a couple of sources, probably strokes, sepsis and surgery that required general anesthesia.

We are in the process of trying to help Mom understand a few things about dementia as she is now his primary caregiver. She has always relied heavily on Dad for any and all important decisions and she is still in that mode. The Recently a psychiatrist told the family that Dad needs to be sheltered from stressful details, particularly the financial mess that they are in. The Dr. said it will cause Dad to become more paranoid, confused and agitated. Mom is having a hard time accepting this. She still insists on telling Dad everything involving his business and trying to keep some semblance of the business going "for Dads sake". I know she can't help it, her world is now upside down and she has never been able to handle change. Mom is sharp and intelligent and she reads voraciously so I was hoping I might find a couple of books that gently explain the changes that dementia causes to help her understand. Something that puts things in lay terms.
Would appreciate any suggestions.