daughter with question

I have a 79 year old mother who has been going through visual hallucinations for 2.5 years, and we do not know what to do. I would like to share her symptoms and receive feed back as to which type of dementia she has, if it is dementia.
Her PCP did the regular Alzheimer’s test, and found she doesn’t have it.
For over 2.5 years, she’s been telling us that Russians are following her and want to kidnap her.She sees them everywhere, and they are following her everywhere. They even send red light in the apartment she lives in to see what she is doing.
She also states that if they have not been able to kidnap her yet, it is because Russia is in war.
Her story is that there is a sect that needs to kill people to make offers to their gods, and she has been chosen to be one of the people that they must kidnap and kill.
She refuses to take medication from her doctor for depression because of their side effects.
We would like to know what type of doctor she should see to give a diagnosis for dementia. I know her doctor must be limited in dementia knowledge.
Thank you.