Your mother's approach to caring for your dad is steeped in tradition and experience. She can recall having heard or visited nursing homes many years ago when they were often
terrible places that warehoused very old and very ill people. She also comes from a time when the marriage vows, including, ""¦in sickness and in health"¦" became bedrock principles requiring selflessness bordering on martyrdom.
My first suggestion is to continue showing your love and support for your mother and dad by visiting and showing concern. In her present state of mind, abandoning her will only make a very bad situation worse. You have to be the rational thinkers in her irrational world.
I suggest that you contact mom's doctor and have his office call her to tell her that it's time for her annual physical and she's due for a flu shot or whatever pretense is needed to get her to see a doctor. There are several issues involved here. The first is it's possible that she too is suffering from cognitive decline. It's likely that she's depressed, and even more highly likely that she is beginning to suffer from the ravages of stress that are caused by being a 24/7 caregiver for your dad, even with some in-home assistance.
Based on the doctor's findings, you may have more say as to either bringing additional help into the home or moving dad to a skilled facility. If events have do continue along lines similar to those your currently experiencing, you're going to have to take some preemptive steps to achieve the best outcome.
Start by telling mom that you love her and you're concerned that she will literally work herself to death trying to do everything and risking her own health and quality of life. If she gets sick, dad won't have anyone to care for him at home. By the way, that statement is more than a "scare tactic." Statistics show that about 66% of full time family caregivers suffer from major illnesses and disease brought on by the stress of caregiving and almost 50% of them predecease their patient.
Other suggestions that might help you include having dad attend an Adult Day Care one or two days a week where he can spend quality time with other Alzheimer's patients doing activities appropriate to his abilities. Dad's doctor, particularly if s/he is a neurologist, might help support this idea as a way to keep dad active, socialized and provide some respite for mom.
Once you can get mom comfortable with leaving dad in the capable hands of others, even for just a few hours, you can begin to discuss with her how wonderful it is knowing that dad is well cared for, and how nice it is for mom to be getting back her life and to a more normal routine. You can, over time build on this theme, with the goal of moving dad to an Alzheimer's facility in the near future. If mom recognizes that her life can be better, she will begin to accept the idea of doing what's best for dad and for her.
Visiting a skilled nursing facility is another idea. If you know of a family acquaintance currently in a skilled facility full time or just for rehab, you can suggest to your mother that you both visit that person, after you take mom out to lunch. Call ahead to let the facility know what you're doing and why, and if they have a dementia specific wing or unit, explain your purpose for the visit. By doing this, mom will see that her images of skilled nursing facilities are out of touch with the way things are in the majority of facilities today.
If you have no one to visit, call ahead to one or two facilities that you have preselected as possibilities for your dad. Arrange to take mom for a tour that includes lunch. Then tell mom that you and she have been invited to go to a lunch, and make sure they give her the full walk-through tour and show her how nice a memory specific facility can be, and share with her the idea that dad's safety and her remaining healthy and happy are key concerns you have for both of them.
Mom may not initially be receptive to these ideas, so be persistent and base all of your comments around your concern that dad needs full time attention. Tell mom that her trying to lift him or maintaining 24-hour vigils has you worried about her health, and her lack of sleep could lead to health problems and you don't want to see her become a patient too.
Your task is challenging, but as a family, you have to continually present mom with choices that she feels are really in the best interest of both she and dad. It's likely going to be very small steps, but you can get there. Having said that, should your mother become ill or injured, you may have to move quickly to make some decisions that assure both mom and dad of a safe, healthy environment that provides for the best quality of life possible for both of them.
For more ideas, search for other articles I've recently written on 3/5 and 3/6 in the archives of Caring.com that also address some of the aspects of your situation.