Since my Dad unexpectedly passed away a few years back I have been trying to make sense of his life, and death really - which is still unexplained. My own mental health struggles are also becoming more of an issue and I'm trying to arm myself as best I can.

For a while he believed his last name was copyrighted and that no one had permission to use it. He got in quite a lot of trouble accusing various authority figures of plotting against him, stealing his money etc.

He would occasionally email me accusing me, my Mum and my brother of lying about various things. For me it was completing university, for my Mum it was where she worked, etc. 

There were also moments of clarity where he would apologise and totally flip into a much softer personality. Sometimes he would email with grand plans to start various business and ask if I wanted to be involved. 

From what I’ve seen so far, schizophrenic psychosis or delusions appear to be more about people interfering with your mind and thoughts - whereas the types of delusions my Dad have seem more real world based.

But perhaps I'm totally off here and this is just a stereotype. Is there anything that really distinguishes the delusions from one disorder and the other, or is it just the accompanying baggage that comes with it that decides the diagnosis?