My MIL lives with us, she doesn't want to continue the tests for Alzheimer's and her other sons support her decision. What can we do?

File for Guardianship. She knows she has failed the initial memory and recall tests. She can refuse to talk to the court evaluator too, but that would work in your favor and the judge will appoint a guardian.

Three months ago my mom had a fall which ended up in a three week rehab stay. While there they did two dementia tests, which she scored poorly on. Up until then I had attributed her odd behavior to the "natural" mental decline that comes with aging. I was pretty uninformed regarding dementia and didn't realize where she was mentally and emotionally was not "natural". To complicate and confuse my opinion was the fact my mom has always been eccentric - for lack of a better word. Shortly after her release her PT suggested I have her retested along with additional tests to get a better, more complete picture of where she was at, and to rule out any trauma from the fall as a temporary contributing factor to her mental state. I declined figuring we already knew she was "off" mentally and since she had had a ton of tests while in the hospital prior to rehab - cat scans, MRIs etc - I wanted to give her a break and focus on her adjusting to her move from IL to AL. I now know I made a mistake. There is some family in-fighting and it may become important to pinpoint as best as possible a timeframe in regards to dementia - to establish her ability to make decisions. Also - her newest move from AL to NH is shaky at best and the next move, if needed, would be to a memory care facility - which would require a more specific diagnosis than what was originally done. I am now trying to get her an appointment with a geriatric psychiatrist. I presented to her as a chance to explore medicines that might help with her memory. So far she's willing and all family members are in agreement that this is a good idea.

How old is MIL?

You apparently already know that she has dementia. Are the further tests to try to determine what kind of dementia it is? That can be useful to you, to know more what to expect, and it can help ensure she does not take drugs that are bad for her particular kind of dementia.

Several things can help in the treatment of dementia: Drugs, staying healthy (nutrition, hydration, etc.), exercise, and how the caregivers interact with the patient. The only one of these impacted by further testing would be drugs. You can manage the others without an official diagnosis or knowing the likely type of dementia.

Frankly, the dementia drugs available now are not so hot. None of them "slows the progression of the disease." Some don't help some people at all. Some help with the current symptoms (which is very worthwhile!). I am highly in favor of trying the drugs, but that can be done without further testing, too.

If you cannot convince MIL to do further testing, I suggest avoiding the drugs that are known to be detrimental in some kinds of dementia (haldol is the most common) and learn all you can about caregiving people who have dementia. You can do just fine without the testing, if need be.

Well, you can't force her to go to the Dr. But maybe try to work on her a little bit at a time.

Let her know that there are medications now that will slow the progression of Alzheimer's and wouldn't she be interested in that kind of medication if she had Alzheimer's?

Why did she discontinue with her testing? Did she become afraid? Did she go into denial?

Since her adult children supported her decision in quitting her testing can you appeal to them to please encourage her to continue? How about a nice, pleasant, non-confrontational email to the adult children asking that they please see if they can get your mom to go back to the Dr.

If your MIL is found to have Alzheimer's she can be put on medication that will likely make her life easier for a while. Without the diagnosis and medication she's bound to struggle. If she had, for example, heart disease or kidney disease wouldn't she want to get a diagnosis and be put on medication to treat the disease? What's so different about Alzheimer's? It's a brain disease and there is medication available.

If you all have been talking to her about this for a while now I'd back off a little, let her think. Don't push her. Then decide upon when to discuss it with her again and pick your time carefully. But know that if she does make the decision to go back that's only half the battle. Actually getting her there is another hurdle.

Ask yourself why it matters that she have an official diagnosis?

Taking cognitive tests when your brain is broken must be agonizing. Those tests are hard on a good day for people with all their faculties. By design, they have to include what you don't know, so most people who are tested end up feeling defeated in some way.