My mother-in-law, who lives alone a two hour drive away from us, her nearest family; who refuses almost all help; who does not meet the eligibility criteria for social care; and who is still waiting on a memory clinic appointment for a formal dementia diagnosis, has meanwhile become delusional. She is so plausible - OTs, a GP, and other professionals have all commented on how 'you'd never know when you meet her' - but over the last few weeks we've discovered that most of what she tells us is untrue. For example, a detailed account of a fall outside a supermarket, passers by wanting to call her an ambulance but her refusing, her shock on seeing the damage to her face in the mirror when she got home ... the whole thing, we discovered today, didn't happen, although she still talks about it as though it did. Yet a few days after the supposed fall she 'remembered' feeling faint beforehand and having pain in her side so we shipped her off to the doctor and she's now waiting on an ECG. This Wednesday she reported a burglary, apparently I'd done it (I actually spent most of that day with my six month old grandson who, unbeknown to MIL, was in the HDU of our local hospital miles away.) The details of the burglary sounded believable enough though - she described returning home to find drawers in her bedroom pulled open and her belongings all over the floor - so we asked her local PCSOs to call. They were fabulous, found no sign of forced entry, no mess (she says she cleaned up) and found most of what she had reported was missing (as expected the rest has turned up since), tried to reassure her that no break in had occurred, and kept in close touch with us. We also asked the GP to call and she checked for infection (none found) and tentatively diagnosed an episode of paranoia. But MIL persists in believing that someone was in her house and has taken her things ... her passport (that turned up inside a book), her credit cards (she only has debit cards, they're both where they should be), cash, her bedside clock (still where it should be) ... next it was her gardener who did it, then the gardener's unemployed husband, then she'd worked out who but couldn't tell me on the phone as 'they' were listening, then it was the Polish immigrants who are watching her house (she immigrated from Poland herself in 1941 and was naturalised British in the 70s). What strikes me about all her delusions is that they are sustained over time, she may lose or change details but she remembers the crux of the thing seemingly indefinitely. I'm too inexperienced with this to know if the long term nature of her delusions is typical. Today she has asked her neighbour to help her change all her locks - the neighbour's stalling on that - seemingly so none of her family can get in. She has a support worker who visits twice a week to make sure she takes her medication properly - for her physical health problems, she's on nothing for her mental state yet - and she reckons he's told her not to trust any of her family and friends (I'm sure he's said nothing of the sort). I'm at a loss as to what we do next. I can't see that anyone will section her and we don't really want them to and yet she clearly cannot carry on as she is, she is extremely vulnerable in her delusional world. Any advice folks with more experience of these things can offer would be most welcome. Edited to add that thankfully my baby grandson is at home again and much better.