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Delusional disorder or dementia?


Registered User
Apr 21, 2015
If anyone has any ideas about this I would love to hear from you. My father is 88. He's always been very self opinionated with some strange ideas about certain things and generally holds the view that he knows everything and nobody else knows anything much. Over the last couple of years his ideas have become more vivid and fantastic to the point where they've taken over much of his life. For instance he became convinced his neighbours were running a cannabis factory, their house was regularly catching fire due to the powerful lights needed etc. although we tried to reassure him we discovered that he had called the police out four times, the fire brigade twice and had also spoken to his other neighbour who is a police officer. All of these people had also reassured him that nothing untoward was going on. These delusions have gradually become more widespread, including infestations of fleas, red dust over everything and fracking going on under his house causing danger to himself and neighbours amongst other things. Matters came to a head recently and he ended up being taken to hospital after being up all night in an agitated state due to the supposed fracking, builders trying to deal with the situation outside, there being a large hole in his bedroom floor and sewage coming up through the floors. My sister stayed with him all night until a doctor and then the ambulance eventually turned up (he's been in his own since my mother passed away five years ago). He didn't seem to have slept, eaten, shaved or dressed for a few days. We think he was spending all his time looking out of the window at the activity he was imagining. In hospital he had loads of tests including a ct scan, which we were told showed no abnormalities, and a dementia test, which we were informed he passed with flying colours. Apparently he also had one at his GP surgery a year ago which again raised no concerns. After a couple of weeks in hospital, during which he continued to recount various theories involving the hospital being built on Victorian tunnels, sewage coming through floors, groups of boys stealing things, fires breaking out at night etc, he was diagnosed with persistent delusional disorder, which having looked up on the internet we felt fitted his symptoms perfectly. He was sent home against our wishes with a care package including support from the mental health outreach team but it was a disaster and after two days he was back in hospital. He was sectioned under the MH Act and admitted to a psychiatric unit for the elderly. When Dad is not recounting these stories, which he does for about three quarters of his time I would say, he is perfectly able to recall and state many details of his life including day the dustmen come, his name, address, date of birth, who we are, names and details of grandchildren, other family members, friends etc. he is taking a keen interest in the forthcoming election, has registered for a postal vote and can complete crosswords. We think he is still able to carry out most self care tasks but will not do so as he is so taken up with his delusional ideas. Now the psychiatrist in charge of the unit has stated she thinks he may have vascular dementia. Our understanding is that symptoms of this might have shown up on a CT scan but this was clear. He had heart bypass surgery fifteen years ago but does not have high blood pressure, has had no strokes or as far as we know any TIAs. Cynically we can't help wondering whether this is a more convenient diagnosis for the health authority who would not then have to pay for his care. When we met with the doctor last week she spoke about discharging him again as he is very keen to go home but this time with a more thorough care plan arranged through the unit using their outreach team. At least this is what she indicated. When we spoke with the unit manager afterwards his attitude changed when we mentioned the possible dementia diagnosis and he indicated very firmly that it would be 'over to social services', reinforcing our view that there might be some resource implications associated with giving the new diagnosis. We are waiting for clarification but in the meantime a discharge meeting has been arranged for mid May. We were told at the meeting that if Dad cannot manage at home then he'd need to go into a dementia unit in a care home but from our previous knowledge of these this would not seem to be the right place for him at all, a point with which the doctor agreed although she suggested it! We are wondering whether we should seek a second opinion and if so how we should go about this. We do have a health and care power of attorney registered. Sorry this post is so long but as I said would welcome any ideas. Thank you for reading if you've got this far!


Registered User
Apr 24, 2013
To be honest this does not fit with any cases of dementia I have come across and seems to be a mental disorder of another kind.


Registered User
Jul 30, 2014
I would definitely seek a second opinion.
My father has vascular dementia and did have delusions, although not so strong and continual, while also presenting as high-functioning and having a good memory. Gradually the latter two have declined. However, white matter changes were always evident on his CT. It may be worth asking the original psychiatrist how she can diagnose Vascular Dementia when the CT shows no white matter changes.