Mom lives in the present and is happy and contented on the whole. I think she lives fully in the present moment, with no worries of the future and no grudges of the past. She remembers little of her past anyway and not remembering doesn’t bother her.
Some others with dementia may suffer from memory tricks where the past is bright and clear, and the present foggy and confused. Such persons seem to be living in the past. They may talk about long dead persons as though they were still alive, and want to “go home” to another home which no longer exists. They are restless and disoriented.
To address disorientation, sometimes caregivers put out artefacts to trigger memories, conversation or even just to provide a familiar welcoming setting. Replicas of homes and items are recreated or purchased and displayed with fanfare. Personally I don’t think it works that well, because no recreation hits the mark for everyone, since everyone has a different past! National Museums Liverpool must be commended for curating items that suits a persons particular past, into a memory stimulating suitcase full of selected items. Do look them up.
Here I’ve cobbled together some examples of dementia care scenes in Singapore: