Has anyone else experienced a relative with BPD becoming completely delusional?
Yes, with my (now deceased) BPD mother, and while this kind of thinking was there all along, I think in an elderly person, other causes can exacerbate them and even cause them without BPD.
Two common causes of delirium in elderly people are urinary infections and medications. There were times when the diagnosis of dementia was considered but BPD mother would return to baseline when she was treated for a UTI or her medication dose adjusted. If your mother is acting more delusional than usual, I would say get her checked for these possible causes.
The more constant concern was the BPD thinking which included these strange and sometimes paranoid ideas about people, and her behavior in general. Being that she remained "legally competent" there wasn't much family could do to intervene on her behalf, even thought it was for her own benefit.
I understand your concern for your elderly widowed mother at home with her BPD. We had this concern as well.
It helps to inform yourself of the resources for the elderly in your country. For me, it's the US- and so learning about Medicare, Medicaid, assisted living, skilled nursing homes- and the laws, and rules for these resources helped to know what was (and wasn't) available to help if needed. As long as my mother remained legally competent (and she did, even with the episodes) intervention wasn't possible.
My best advice to you in this situation is to have someone designated as POA and Medial POA for your mother so it would be possible to make decisions for her if needed. It can be you or another family member if they are trustworthy and would act in her best interest. Also inform yourself of resources available to her- assistance at home, assisted living, nursing home care- if they were ever to be needed. Most important- get support for yourself through counseling, maintain self care.
With the medical POA, I was able to speak to her doctors and health care providers. In BPD mother's situation, "BPD" was not a helpful label. It made more sense to address the issues that were a cause of discomfort for her- her anxiety was a main one and there is medicine for that. Your mother can access therapy and medication without the BPD label - with other ones such as "anxiety". DBT therapy is known to help with BPD and she may need the label for that but she would need to be motivated to do it.
