Love seems to be the most basic and primary essential. It is important to realise that, despite the mental problems, an Alzheimer patient can still retain emotions. For example, my wife's mother could still readily play the piano and accompany her young grandchildren's singing, despite having Alzheimer's Disease of such severity that she could not string together two intelligible words. Dementia in general is associated with an intellectual deterioration in an adult which is severe enough to interfere with both their work and their social skills. The changes in mental processes not only involve disturbances in memory but also in perception, the ability to learn, to solve problems and to think abstractly and make judgements.
Senile dementia is simply dementia in the aging adult.
This may be a consequence of Alzheimer's Disease but there may be other explanations, for example the effects of several small strokes. The duration of the disease is long, often five to ten years from diagnosis, and sufferers may spend the last five or more of those years under close care at home or in a nursing home. Individuals who are well looked after may survive physically even if they have a total loss of mental processes. Death often results from other diseases - for example, heart disease, cancer, stroke or pneumonia. The decrease in life expectancy associated with Alzheimer's Disease makes it the fourth or fifth leading cause of death.