Delusions are false beliefs. In the patient's mind, delusions are real and no amount of reasoning will change them. The best tactic is not to challenge a delusion. Sometimes, to try to change a delusion can bring violence on the part of the patient. Think of a delusion as the result of a broken cable in the brain. Reasoning won't reconnect the broken cable. Sometimes antipsychotic medicine can help if the delusion is recent and not very specific. If the delusion has been established for a long time, and is deeply rooted, antipsychotic medicine won't work. We called them fixed delusions.
I know when I was the subject of such a delusion a couple of times (first that I'd been locked in the trunk of someone's car, later that her health aids had kidnapped me to do their dirty work), a reassuring phone call or visit cleared it up. But it had to come from me because she wouldn't believe anyone else. They were all "in on it" or "too naive to understand."
There really is no way, I think, to convince a delusional person of anything whatsoever. I am sorry for your situation. Do know that in most people who are severely delusional, things do often move on from one obsessive thing to another with time.
Just last week my 86-yr old MIL who is in LTC had the staff call us at 9:30pm. She urgently insisted that "Jeff" (my husband's brother) was missing and no one had heard from him and she was extremely upset about this. Jeff lives several states away with his wife, we live in MN near my MIL. She has never done this before even though she's been in a facility since 2016. We opted to tell her a "therapeutic fib" because it would bring down her anxiety quickly as possible. We told her Jeff was visiting with us and perfectly safe but was in the shower and couldn't come to the phone at the moment. This satisfied her. We then asked Jeff to call her right away. She has short-term memory loss so we're not sure if she even remembered she had this delusion, but she went to bed in a calm state and that's what matters.
Your mom having this delusion in the first place is a different issue.
Is this an ongoing thing, or did it start suddenly and recently?
A sudden change in mental status (as when some suddenly starts having delusions) is a medical emergency. In some elders, urinary tract infections can cause mental and behavioral changes without an accompanying symptoms.
Your mom having this delusion in the first place is a different issue.
Is this your mother's only delusion?
Is this an ongoing thing, or did it start suddenly and recently?
A sudden change in mental status (as when some suddenly starts having delusions) is a medical emergency. In some elders, urinary tract infections can cause mental and behavioral changes without an accompanying symptoms.
Have you spoken to her doctor?